4L80E...

QUESTION:

Tue Oct 14 20:36:51 PDT 1997
Oh boy here I go again with one of those intermittent problems. Problem is intermittent code 87 by itself with no other codes, which put the transmission in 2nd gear along with max. PSI. I put my Snap-on Scanner on it and got it to act up and recorded a movie. It makes a 1-2 shift then the ecm commands a 2-3 (solenoid 'B" on), and no upshift to 3rd . After 2 seconds of no upshift code 87 tripped. Ratio stays at 1.48 while the ecm commands 3rd, and rpm verifies no upshift took place. I looked at the recorded movie with the scangrafics, but everything is steady, from range sensor to inputs and outputs. The truck has 10,000 miles on it. PSI test shows all pressures normal. I had to drive it about 30 miles to get it to act up. I carried it back to the shop and hooked up the TransX2000 to see if actual voltage is being sent to the 2-3 solenoid. After another 30 miles of driving I gave up on seeing it act up. So I pulled the pan and replace both shift solenoids, and even through in a manifold PSI sensor. Drove it 1 mile and here goes code 87 again, this time it caught me with my pants down, (no scanner or TransX on it, stupid me). I drove it another 50 miles with all equipment on it, but no problems yet. Fluid is cherry by the way. I am sure the direct clutches are in good shape, because I can load test (stall) them with the TransX2000 and watch the turbine sensor for slippage, so internal slippage is not likely. I think I'll pull the valvebody tomorrow, and rot out the solenoid feed holes, and replace the screen that breaks under the manual valve. Any one got any ideas? I remember reading an article in gears about the solenoid feed holes being a little to small, but I don't remember which issue it was in. Man I hate remembering reading something and forgetting where I read it at. Does the Trans Doctor tell where that article is? This is about my 3rd experience with a code 87 by itself, and each time so far it's been something different.
Dan Tucker

RESPONSES;

• Tue Oct 14 21:13:17 PDT 1997
  My book says a code 87 is solenoid "B" stuck open. Since you already changed the solenoids, make sure the shift valves are not sticky or drag with the solenoids off. You can move the valves with the solenoids off, without removing the VB. A broken feed screen can cause this problem too.
  Sometimes a bad ignition switch will cause solenoid codes after 15 minutes of driving.
  I doubt that this helped, but atleast I took a shot at it.
  Keep us posted on your progress.
  Bill

• Wed Oct 15 06:27:05 PDT 1997
  It does sound like the shift valve may not be moving. The other possibility is a loose wire connection. If it's not happening when you have all the equip hooked up, you may want to take a real close look at the wire looms, and the connection at the trans. Make sure there is no trans fluid leaking through the case connector. They updated the harness to a quick connect trying to get rid of the leaking problem. However it still leaks. They did have many problems with the early screw in type connection.
  Yogi

• Thu Oct 16 11:28:50 PDT 1997
  DTC code 87 indicates that PCM is commanding 3rd or 4th but the TISS and TOSS are indicating 1st or 2nd,it could be a stuck open solenoid or it could be a stuck shift valve. It could also be caused by a direct clutch that won't apply(burn't),usually from a broken cushion plate. DTC's 86 and 87 are indicating mechanical problems,the PCM is commanding shifts and not seeing them.
  Hope this helps
  Jim Bockus

• Fri Oct 17 05:27:35 PDT 1997
  Code 87 is very misleading, it is actually a gear ratio error. It sets when the computer commands 3rd or 4th gear but sees a 1st or second gear ratio.
  As you stated your scanner is showing a 1:48 gear ratio. The single most important thing is, this code is caused by a mechanical problem, NOT electrical.
  Since you have changed both solenoids, check the solenoid feed screen located in the manual valve bore.
  Check ATRA bulletin #333, it shows you where to drill the solenoid "B" feed orifice in the spacer plate to .041.
  Rick Anderson

• Sat Oct 18 19:12:50 PDT 1997
  I was thumbing through the TransGo electronic transmission book and found that a code 87 can be generated by a broken acuator filter.. the filter behind the manual valve.
  What you might have is a partialy broken filter that seals up for most the time but will shake loose and create your fault.

  
  

FIX:

Wed Oct 15 19:42:51 PDT 1997
Yogi & Transman,
Thanks for the replys. Yogi you mentioned that it may be a loose connection (case connector etc), but I think it would have to have some other codes along with the 87. One way I go after finding intermidant codes is clear the codes and try to reproduce the exact codes. If you pull the pan on a 4L80E and disconnect the B solenoid you'll get codes like 81 or 82 because the ecm sees loss of connection. Also I took a movie and when the malfunction took place and the computer commanded 3rd, but the transmission didn't shift to third, the circut feedback to the ecm was OK which means the connection was good during the problem. So my conclusion is the ecm is satisfied that the solenoid operated electically. So I replace it to know that the solenoid operated with fluid. So the problem has to be did the 2-3 shift valve stroke? If it did stroke, then did the oil get delivered to the direct clutch? That is a good question. Let's look at the transmission like it was a 400. If the shift valve were to move and it took say 3 seconds before the direct clutch overcame a small internal leak, and then over came the leak and applied the clutch all at once would we notice it? Probaly not, it would just delay the shift slightly and more than likely go unnoticed. But becauce the ecm is 'birdogging' that clutch, it better come on pretty quick after it COMMANDS it to be on, or it throws us an 87. The kind of delay I am talking about is like a A4LD delaying reverse, then when it comes on bang. No burning of the clutches on the A4LD, just a delay. What do we do to correct it on an A4LD? We enlarge the reverse feed orifice and it's fixed. This brings me to what I think the cause of the 96 4L80E code 87 really is. The 3rd feed hole on the 1996 was only .052. I mic'ed several other older 3rd feeds in the seperater plate and the smallest was .072. We'll you know what I did.....I opened that baby up to .090. I also opened up the solenoid feed holes from .022 to .035, so I know the solenoids have enough oil to stroke the shift valve. This is all I did, and I've driven it 50 miles so far and praise God it's shifting great. Of coarse only time will tell but it does make sense. I am in no way making this post to knock anyones ideas, or try to be a know it all, but only to further all of our knowledge. I've done a lot of research on the code 87 and thought I should share it with TRNi. I'm just like everyone else on TRNi. I'm here to learn from other peoples trial and error. It's a great network!
Dan Tucker

4L60E...

QUESTION:

Tue Oct 21 19:04:08 PDT 1997
We have a 1993 Suburban with a 4L60E transmission in it, that came in for a rough 1-2 shift. The shift would make the tires bark. Scanned computer to find a code 73 that has to do with current to the pressure force motor.
My technicians replaced force motor and still end up with the same code and still has a hard shift. We are wondering if anyone else has had this problem before we start changing the TPS, VSS and last but not least the ECM. I am unfamiliar with this code 73 and Snap-On has nothing listed on the Troubleshooter.
Thanks in Advance.
Don Stone - ASA Florida VP
AAA Quality Transmissions

RESPONSES;

• Tue Oct 21 19:25:13 PDT 1997
  I've never had that problem Don.
  But I have some info on code 73 for you.
  Force motor incorrect current.
  Possible cause:
  Broken wires, bad connections or possibly a bad solenoid coil. But it is rarely the solenoid coil itself.
  Also check solenoid connection and case connector. A scan tool will display commanded (desired) Force Motor current as well as Actual Force Current. In a normally functioning circuit both will read nearly identical. Watch for variances between them to determine if system is operating correctly.
  If Desired Force Motor Amps (FMA) and Actual Force Motor Amps both rapidly toggle high/low, suspect a shorted solenoid or shorted wires. If desired FMA is higher than Actual FMA suspect an open circuit or short to ground. If Actual FMA is lower that desired FMA, suspect a short to power.
  Hope this helps..
  Let us know how it turns out!
  Bill

• Wed Oct 22 04:01:48 PDT 1997
  When ever I have a cold shift problem the first thing I try is a complete fluid and filter change. I disconnect the return line and pump out the conv that way. Being it was a used unit maybe it wasn't 100% clean. It's worked for me quite a few times on 440.
  Your solenoids may also be clogged . If you have a shift box you can pin point if it's in the trans or the computer system. Those VSS can also be a problem.

• Wed Oct 22 05:09:38 PDT 1997
  Don,
  Code 73 will set if the force motor current returning to the PCM is .16 amps higher or lower than the current sent from the PCM. When code 73 sets, the PCM shuts off all current to the force motor which causes maximum line pressure in the transmission. DTC 73 will only set if the force motor is shorted to ground or shorted to voltage. DTC 73 will not set if the force motor is internally shorted because the amount of current being sent by the PCM is returning to the PCM.
  I would disconnect the case connector and check for presence of fluid, and check all wiring from PCM to transmission. Hope this helps, Jim
  Let us know the fix
  Jim Bockus

• Wed Oct 22 17:56:36 PDT 1997
  Don,
  Before you start changing parts on this 4l60E I would put a gauge on this thing. I've experienced very harsh 1-2 shifts on these in the past and we have always found it to be caused by a high line condition. You would think all of the shifts would be harsh, but on this trans only the 1-2 shift seems to be affected by it.
  Rod

• Wed Oct 22 19:13:35 PDT 1997
  Try disconnecting the battery to clear the codes and reseting to normal values.
  RADRON

• Thu Oct 23 04:52:12 PDT 1997
  Don, most of my run-ins with code 73 have NOT been related to the force motor circuit at all.
  This code has been caused by problems with system voltage. Start with battery check, charging system voltage and voltage drop tests on ground circuits. Certain truck models have a ground attached to the thermostat housing bolt, a very unfriendly environment.
  Rick Anderson

• Thu Oct 23 05:09:02 PDT 1997
  Attn: Don Stone-- Code 73- This is purely an electrical problem with the Force Motor wiring circuit. Extremely unlikely to be an ECM problem. Dont start swapping TPS, VSS, etc. Follow wiring (visually only) from trans to ECM
  Somewhere it is likely broken or shorted/pinched to ground. Look close at hold down bracket on bell housing bolt. They will rotate and cut into wiring.
  Paul

  
  

FIX:

Mon, 3 Nov 1997 23:07:07 -0500
Just thought I would send out the fix for the 93 Suburban that would chirp the tires at 20 MPH.
We connected the old Shaeffer Shifter on the vehicle and the Transmission worked fine. We then traced the wires from the ECM to the trans and they were good with no breaks in the wiring. Now we pulled about 2 more hands full of much need hair from our heads and assumed the ECM was faulty. The code 73 would not disappear.
We ordered an ECM from the dealer for the next day and also send out our problem out to TRNi members the same night. In the morning when I got to the shop I checked our e-mail and we got a message from some members to check battery voltage and charging system. Well a two by four just hit me in the head after remembering my techs jump starting the vehicle. We swapped the battery for a good one out of a Taurus we were working on and low and behold the Transmission worked perfectly. Of course when the dealer showed up with the ECM we sent it back.
The customer was more than happy to purchase a battery instead of a transmission and it was all a result of TRNi members and this network.
All this work for a bad battery.
Thanks to all that replied.
Don Stone - ASA Florida VP
AAA Quality Transmissions
Stuart, Fla.

More 4L60E...

QUESTION:

I am seeing a pattern of 1996-1997 4L60e's come in with a code P1870, which in common transmission English is RATIO ERROR. Now I realize that just about any component in the transmission slipping could trip the code, but it seems to be, the TCC not engaging that is usually the cause. I have one right now that I'm working on. It locks up fine when cold, but after it gets warm, the VCM commands Lockup, but the TCC slip is well over 150 rpms, and no lockup is felt. I've hooked up the TransX2000 and monitored the actual voltage to the transmission when the VCM is commanding lockup, and the voltage is being sent from the VCM. Next I override the VCM and apply the lockup with the lockup feel PWM duty cycle at 40%, no lockup, BUT if I raise the lockup apply feel PWM duty cycle to above 55% it works. Does his tells me the oil PSI in the TCC apply circuit is too low? Sure sounds good, especially being that it only does it when hot. I've been replacing the pumps and the converters to correct this condition, but I can't see a thing wrong with them, though it does solve the problem. I know that we put in a few AODE converters before we found an easier fix. SO, here I go into the "what if" field. What if we could somehow raise the TCC apply feel PSI that was being sent TOO the PWM TCC solenoid, would it help, or even correct the no lockup condition? I looked at increasing the TCC apply feel valve spring, but the spring the factory has in it, looks like it has been taking steroids already. I think I may shim the spring tomorrow and just see. I wonder what would happen if I just blocked the apply feel valve? Here is another thought, what if we unplugged the lockup apply feel solenoid, and just plugged up a dummy solenoid to the wiring harness to satisfy the VCM? Any body got any ideas? You know I am beginning to dislike the letters PWM!
Dan Tucker

RESPONSES;

• Fri, 07 Nov 1997 09:15:42 -0600
  Gentleman; If you add a spring to the isolator(pushing isolator toward regulator valve), or increase PWM oil to the isolator,the regulator will stay in a max. flow position. But...the regulator bore is often so worn out that converter apply oil leaks too excessively to control/hold the TCC clutch when hot. Until this is addressed, numerous shops are bloking the regulator to max. on RWD units. This is too severe on the 4T60E. When the bore and valve are worn, your converter apply oil goes out the window to exhaust. Inspect and Wet/air test the regulator valve. (keep this in mind on all the PWM GM's.)The regulated PWM converter apply circuits are not routed oil from the pressure regulator valve as in "the good ole'days. The 4L60E pwm oil circuits are not correctly illustrated. If you work through signal and apply circuits you will see this. Good Luck...isn't this fun!
  BWsonnax

• Fri, 7 Nov 1997 23:01:16 -0600
  BW SONNAX
  First thanks for spending your time on the net. Sonnax products and research are a asset to the rebuilding industry. How do you recommend that we set the PWM to maximum? I, like you, am uncertain about the literature on the 4L60E. I think until we get a fix for the 1996 and up 4L60E transmission we may need to consider 'bypassing' all PWM.
  Dan Tucker

• To clarify what was meant by setting/getting full PWM oil is...opening the plate orifice between the plug and the solenoid. This is about all you can do to assist TCC/PWM boost. If you increase actuator feed oil, it could flood the shift solenoids (example,4L80E)
  BWsonnax

• Tue, 18 Nov 1997 11:21:51 EST
  BWsonnax,
  In your reply on this subject you say "numerous shops are blocking the regulator valve to max. PWM".
  Could you elaborate on how they are doing this ?
  Ron Widing
  Widco Transmissions
  Griffith, IN

• To clarify...blocking the "converter regulator valve in the valve body" will allow full line psi to flow to the apply circuit. Blocking it means...the two spooled valve must remain towards the end plug and clip on the 4L60E.
  If you examine these valves they are set up similar to a line pressure regulator. They have a boost/isolator plug and a balance circuit. Keeping the valve in the high flow position allows higher apply psi. to the converter. (This pressure must flow through the converter TCC valve in the pump after the regulator valve.) I'm NOT a fan of putting Band-Aids on problems, such as this procedure. But at this time your options are limited.
  BW

  
  

FIX:

• This is the follow up on the P1870 TCC slipping when hot, on the 1997 Chevy truck. Well after pulling the pan 4 times it's fixed! I'm not going to tell all the stuff I did that didn't work. The final fix was to grind 2 flats on the apply regulator valve and change the spring tension on the apply regulator valve to a inner pump slide spring from a 200r4,700,4l60E. I tried grinding the flats on the valve first, but somehow I lost lockup all together. So I put in the slide inner spring and this 4L60E locks up like a 700! No more mushy...sliding....PMW-hindered Lockup. It's NOT too firm, just right. I can't figure out why any of the automakers like the PWM lockup anyhow. I just kind of grit my teeth when I see the computer command TCC lockup and it takes 2-3 seconds to see the TCC slip to get to 0. Maybe I'm weird, but I feel sorry for that converter clutch getting fried by the PWM system. I think the next time I will try just the inner slide spring by itself to see how it works.
  Dan Tucker
  

• Wed, 5 Nov 1997 20:11:56 -0500 (EST)
  Dan, How many miles on these units that loose TCC hot and set code? I have to agree with your first impulse that TCC apply is low. With a new converter will they lock up solid when hot, with 40% TCC duty cycle? The spring in the regulater apply valve line up does not set regulating pressure for the tcc apply. It is just a bumper for the isolater valve. PWM solenoid output oil acts on inboard end of isolater valve which pushes bumper spring against regulater valve. Therefor regulated converter feed oil is dependant on PWM sol oil and balanced against TCC apply oil. If you want to try to raise the initial TCC apply then a spring on the inboard end of the isolater valve would be the place to start. This would be like the 4T60-E tcc reg valve line up. Whatever you do, make sure the compressed (solid) height of the spring isnt taller than the stem of the valve. Also, is there any possibilty the isolater valve bore is worn out? If you can crimp a length of steel tubing on the stem of the valve it provides a handle. Poke it into the bore and wiggle it side to side and up and dowm. The bore may be worn. This has been known to happen before and installing a fresh converter will stop it for a while but not forever. As it wears it will likely get more worn even faster. Interested in fixing this problem.
  Paul

• Paul,
  I think my e-mail is about as messed up as some of these transmission we have to contend with. The last unit I worked on had 39,000 miles and the valve lineup was visually tight, though I didn't try your method of analyzing it for wear. Both the regulator and isolator valve were made of aluminum. After I ground the regulator valves outermost land, and it totally knocked out TCC apply, I replaced the isolator valve with a steel valve and installed the pump slide spring. The steel isolator valve also was different in physical appearance (tits on both ends) the outside dimensions were the same. I really don't know rather the new isolator valve or the spring or the grinding of the regulator valve, corrected the TCC lockup, but I know 1 of the 3 fixed it. The oils schematic I had to go by was a faxed copy and you how easy it is to read thermal paper, so I was almost in the dark. ATSG recommended the valve grinding. Is there a problem with the 4T60E doing the same thing? I haven't seen any TCC slip codes on them, YET. Do you know a fix for by-passing the PWM on the 4T60E? What would you do to by-pass the PWM on the 4L60E? Would it work to just unplug the PWM solenoid, and leave it in the bore, then install a dummy PWM solenoid to the wiring harness to satisfy the VCM? This truck locked up fine if I raised the duty cycle to above 52 % when hot, and lockup was fine with the VCM controlling the apply when cold. I think that the valve grinding would have worked, but the factory spring is so short that when the apply oil hit the converter it backed up and by-passed the unregulated oil to exhaust, because of the short spring. But I am a little out of my league, this is only a guess.
  Dan Tucker
  

• Mon, 10 Nov 1997 22:19:29 EST
  Paul,
  I was going to check out your idea of putting a spring on the inboard side of the "isolater valve", but none of my references show an isolater valve. From your description it sounds like what my illustrations call the boost valve. If this is the one you are referring to, do you mean put the spring down inside the boost valve sleeve ?
  Ron Widing
  Widco Transmissions
  Griffith, IN
  

• Wed, 12 Nov 1997 06:37:02 -0500 (EST)
  Subject: Re: TRNi: 4L60E 1997 P1870 (slipping) No TCC engagement.
  The boost valve and isolater valve are not the same thing. If you don't have a late book then the valve line-up I mentioned will not be shown. This valve line up was not in pre 95 models. Only later models with PWM have this. In all the GM books I have it is called the isolater valve. I don't really know what else to call it.

518...

QUESTION:

Wed Oct 1 17:30:11 PDT 1997
Anybody dealing with any 42RE's in Jeeps? Got one that intermittently starts in 2nd or 3rd gear usually worse hot. Governor pressure drifts up to about 20-25 psi standing still. Can watch Duty Cycle signal to gov sol command it and watch gov pressure sensor track it. Also temp sensor shorts to ground when hot (loses 4th) but even when its not shorted, pig don't work right. Already has new GP Solenoid and GP sensor in it. Just wondering if anybody else has seen this.
Tod?
Thanx-Paul

RESPONSES;

• Wed Oct 1 18:29:33 PDT 1997
  I've run into this before, but it was a while back. If I were at the shop, I could tell you exactly, but as I recall it was a bad gov. pressure sol., that comes attached with another sol.. They're accessible from the pan, but I think I had to drop the valve body.
  I'm sorry I can't be specific on the proper names. I think there are 2 electronic devices dealing with the gov. cicuit on the v/b. The one causing the problem was harnessed with another sol., I just can't remember which one it was.
  Good Luck,
  Kirk Mahaffy

• Wed Oct 1 18:59:12 PDT 1997
  Hey Paul! That's my pig! You didn't say what model year though, been in production since 94 and has had 2 different controllers. If you changed the governor pressure sensor and solenoid, and you still have a problem, it is either controller or wiring. You say the duty cycle commands the higher pressure (25 psi)? I assume you have a DRBII or other device attached to the controller. There should be a display with the duty cycle and governor set point available. Does it request 25 psi or does the duty cycle continue to reduce at idle until 25 psi is reached? This is a closed loop system and the duty cycle will relax until the controller sees it rise off 0 psi and then it will increase to pull it back to 0. If the duty cycle is reducing then it thinks it is already at 0 psi. What pressure does the scanner show in idle? There is no lp feed to the gov system in neutral and park so if you see pressure then you can assume there is a problem in the sensor circuit. Let me know if you have any other questions.
  Ken Potter

• Wed Oct 1 21:08:32 PDT 1997
  Paul,
  Yes, I have seen this problem before. Hmmm, a govenor pressure sensor usually fixes it. I did have one that had a broken pin in the case connector. Drove me nuts. If it's not the solenoid, or the transducer, then check wiring and/or TCM. Jeeps have a seperate TCM I believe. Not too many problems though. Check wiring closely.
  Good luck. Please let us know the fix.
  Tod

• Wed Oct 1 22:03:45 PDT 1997
  Hey paul, vss sensor can cause all kinds of problems, also tps sensor. let us know the fix. tks. robert

• Thu Oct 2 06:36:19 PDT 1997
  I don't know what truth this holds, but I hear there are MANY crossleak problems within the vb itself.
  If there is gov pressure in N than I have heard that flatsanding every single portion of the vb will correct this complaint. I havn't seen one of these units yet, so I can't really say I've tried it. I would be more apt to believe that the 1-2 shift valve is hanging or the spring is too weak.
  Yogi

• Thu Oct 2 16:52:16 PDT 1997
  It is true that there are a number of problems with cross talk on these valve bodies, but they show up early in the life of the trans. Flat sanding (we lap them on a lapping table) goes a long way to removing the leaks. Primary focus should be transfer plate it seems to be the biggest problem. It also seems to help if you use a torque wrench when you assemble the valve body and put it into the case. The plant has improved this problem effective July 1st of this year.
  Paul's problem sounds electrical, assuming this is not an infant mortality problem. Broken pins on the connector are not uncommon, also terminal push-out on the female side. If you have a scanner, check the codes and also verify the pressure sensor is between .350 and .800 volts with the trans in neutral.
  Ken Potter

FIX:

42RE- It Lives- 42RE is fixed-- Here is info for every one including info for questions asked.
The Jeep is/was a 94 model. Installed both a new GP Solenoid and sensor-same problem-20-25psi gov pressure and 2nd or 3rd starts. Also listed in the original post was info on temp sensor voltage going low (.04 volts) when hot and losing 4th gear. I was monitoring gov solenoid duty cycle and gp sensor voltage with digital graphing multimeter. Both would dither and fluctuate together and drift up to produce high gov at standstill. Hard to know if sensor is faulty or skewed and command is trying to deliver pressure command signal to make it read right or is solenoid faulty and sensor correct? Anyway both new didn't fix it. Decided to fix what could be proven bad-temp sensor. Replaced ONLY the temp sensor from a "donor" vb I had. I got a tip (thanks Wayne) that Chrysler allegedly had a problem with temp and GP sensor grounds being tied together and on new design harnesses are seperate (true Ken?) . So I separated mine and gave temp sensor its own ground since I was splicing it onto the original harness anyway. All back in and works fine hot and cold. GP Solenoid and sensor are steady and correct and work in proportion to vehicle speed. One last thing I didn't mention or pay attention to before was the GPDC and GP sensor volts wavered up and down at 55 mph. After "fix" it was steady as a rock. Temp voltage hot was approx 3.3v instead of .04v as before. No loss of 4th either. Good diagnostic tip from Ken Potter on GP sensor- If sensor voltage is high in park or neutral it is a bad sensor/circuit, not solenoid-there is no feed to GP sol in P or N so even if it was stuck open wouldn't make high sensor volts. At this time (in some ways) not all this problem/fix makes total sense to me. I have found before if you see something definately wrong even though it may not SEEM to be directly related to your problem, that many times it is.
???????
Paul

MORE!!:

• Mon Oct 6 05:29:58 PDT 1997
  Ken Potter- Thanks for info on sensor grounds. Is there any reasoable explanation on why a bad thermister should interfere with proper gov. system functions?
  Paul

• Mon Oct 6 17:23:44 PDT 1997
  Paul,
  I suspect you fixed the problem by fixing the ground, which is common to both devices. That controller can output codes through the OD OFF lamp. Use the usual 3 key-on sequence like you use for engine codes and count flashes on the OD OFF lamp. Codes are stored until power is disconnected from the module or a clear codes is sent by a DRBII. You will probably find codes set for the temp and pressure sensors, which is the clue for bad signal ground to the transmission.
  Ken Potter