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Thread: 94 Car with 95(?) Transmission
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10-20-2014, 11:26 AM #1Lurker
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94 Car with 95(?) Transmission
I already posted this at LS1Tech's LT1-LT4 forum, but thought I might have better luck here (apologies). Kind of long but I think I have all the details I know.
I've got a 94 A4 that's been tuned like a 95. The trans is aftermarket, was in the car when I got it, had about 1000 miles on it when the engine fried and it came to me a couple months later. After the engine swap (stock replacement 94 Trans Am engine with 41k on it) I discovered that the trans is at least a 95, since it has PWM stamped on the pump housing.
So- when I got it running again, I didn't know the trans was PWM, got a hidden code 84 (3-2 downshift solenoid operation error). Limp mode, no OD, no TC lockup. I talked to my tuner and had the PCM flashed as a 95, ran a wire from PCM D6 to case connector pin U. That should have done the trick. I haven't tried to pull codes to see if the 84 is still there, but the behavior hasn't changed. No 4th gear, limpy starts.
Today I got a chance to check some things on it. I checked the resistance of the solenoids to see if one was out of spec. First I completely disconnected the battery and got values that were all above the spec. Then I connected both battery cables and got nothing at all. Then I disconnected the battery negative only and got these, which I think are legit values:
1-2 solenoid: 22.3 ohms; spec for 95 is 20-40 ohms
2-3 solenoid: 22.4 ohms; spec for 95 is 20-40 ohms
3-2 solenoid: 11.8 ohms; spec for 95 is 9-14 ohms
TCC solenoid: 29.3 ohms; spec for 95 is 20-40 ohms
PWM solenoid: 12.0 ohms; spec for 95 is 9-14 ohms
I just put the meter in the PCM connector pin holes with the - side and the + side of the meter to the batt + block in the pass. side fender behind the batt.
When I first ran the wire for the PWM solenoid, the battery would drain to dead in about 2-3 days. It's been a while since I had a chance to do anything with the car. Thought I had misplaced the pin at one end or the other, that's why I did a sanity check to see if I saw correct resistance in the solenoids at the trans end, or possibly a ground fault. That tells me the wiring is right at the case end, and the only thing I touched at the PCM end was add the wire on D6. I'm stumped for the moment.
Anything else I can cover with a multimeter before I assume there may be mechanical damage to the trans? This is a K-case trans that would be worth rebuilding but $7-900.00 is more than I can swing right now. May look for a used 95 from a known F-body in the interim.
I saw from Frank Cahall's sticky that "'94 computer won't recognise new TCC strategy, and will burn lock-up clutch and 3-4 clutches up." I wonder if this has already occurred over the 1000 miles or so it was run in the car with the original '94 factory tune.
Thanks"Doc Opticus" '94 Formula M6 hardtop: 377RWHP, 371RWTQ My 93-94 Opti mod: http://www.ls1tech.com/forums/lt1-lt...-94-folks.html
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10-20-2014, 11:26 AM #2"The Rock"
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10-20-2014, 12:45 PM #3LTXTech Sponsor
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When you're referring to "Limp Mode", you mean 3rd gear starts and high line pressure? If it's in limp, it won't have 1st gear.
FrankGail C. Cahall
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10-20-2014, 12:55 PM #4Lurker
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Correct- max line pressure and 3rd gear start mode, etc per GM ("soft landing mode"). I really need to check again to see if the code 84 is gone with everything connected. Thinking back on it, I may have caused an unrelated issue with a drain to ground that's coincidental. I was trying to get the driver's door master switch working consistently to cycle the locks. I'll unhook the master window switch and see if the batt drain stops, and scan for the code 84. May be just coincidence on the batt drain, and the logical fault is actually gone by running the wire and updating to 95 tune, but I don't observe a change in how it's working due to mechanical damage. Thanks for the help- I'll get back with an update as soon as I can with more info.
"Doc Opticus" '94 Formula M6 hardtop: 377RWHP, 371RWTQ My 93-94 Opti mod: http://www.ls1tech.com/forums/lt1-lt...-94-folks.html
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10-20-2014, 01:13 PM #5LTXTech Sponsor
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If it's in limp mode then it has to have a code. Have you checked for 12 volts at pin "E" in the harness?
Gail C. Cahall
CAHALL PERFORMANCE TRANSMISSIONS
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10-20-2014, 02:47 PM #6Lurker
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In the past I've had difficulty getting the case connector off without first supporting the tailshaft housing with a jack and unbolting the trans mount and letting it drop a little. But no big deal to do that if need be to get at pin E in the case connector. Just a pain with the cooler lines in the way and the tunnel so close on top. Is there a trade secret to getting the case connector on/off without partially dropping the trans? It seems that Pin E provides power for all the solenoids in there. If none of them were getting power due to a fault with pin E, what would the behavior be? Same or (?)
Sorry for all the questions. Just trying to get my head re-wrapped around the problem and maybe come up with a solution this time."Doc Opticus" '94 Formula M6 hardtop: 377RWHP, 371RWTQ My 93-94 Opti mod: http://www.ls1tech.com/forums/lt1-lt...-94-folks.html
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10-20-2014, 04:04 PM #7LTXTech Sponsor
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No power to pin E will put it in "limp mode". I usually don't have that much trouble getting the case connector off. It's pretty tight though.
Gail C. Cahall
CAHALL PERFORMANCE TRANSMISSIONS
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10-20-2014, 04:11 PM #8"The Rock"
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Just wanna say thanku to Frank. He never lets us (this community down)...
Our BIG MOMENT @ the 2012 LTXshootout
http://www.facebook.com/photo.php?v=521756391174175
1996 Camaro Z28: RIP 09/25/2016
1994 Trans Am GT: SOLD 05/2017
1985/1996GS clone: SOLD
1996 Impala SS H/C, LT, with true dual exhaust, 4.10s, lowered, with CPT trans, many cosmetic mods, and a whole lot more to come...
2002 Caddilac EscaladeL CAI, lowered, 6.0 , AWD..
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10-21-2014, 08:09 AM #9Lurker
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"Doc Opticus" '94 Formula M6 hardtop: 377RWHP, 371RWTQ My 93-94 Opti mod: http://www.ls1tech.com/forums/lt1-lt...-94-folks.html
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02-20-2015, 02:14 PM #10Lurker
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I haven't been able to spend any time with the car to get firm answers to helpful questions, sorry about that. Car's in an outbuilding at our old house, presently rented out (we reserved the outbuilding). Hit the busy (silly) season and it's been cold as crap since. I know, NC folks don't know anything about real cold compared to folks in the Northeast right now. In the past I've built cribbing under the car to hold it securely with no chance of moving/ falling while I do work underneath. The pre-work setup will take up some time the next time I get over there. Just weird wrenching at somebody else's house who you only know because they rent from you.
Here's what I do have to add until I can get some real data to share:
1) If the ignition feed circuit (circuit 239, fuse 11; provides power to all solenoids) is open, multiple DTCs will be set (per GM service manual). Since I only have one DTC- code 84, my gut tells me there will be power at pin E. In my notes from April 2011 when I first discovered the issue putting the car back together, I had continuity at pin E from PCM pin B29 (5 volt reference).
2) I re-read Frank's details on the 95 trans in the 4L60e sticky here and one over at ImpalaSSForum, posted there by member V8killer. There was mention of the 3-2 downshift changing around mid-year from 9-14 ohms to the 20-31 ohms solenoid. I don't know if that refers to solenoid change and corresponding PCM programming in just the B-body cars, or all car lines. I'm not sure where to even look in my F-body PCM programming to find what value range the PCM is looking to see. It'd be hilarious if changing the 3-2 solenoid to the 96 style fixed it. I hate to throw parts at anything, but I might pick one up as something to try while I'm at it."Doc Opticus" '94 Formula M6 hardtop: 377RWHP, 371RWTQ My 93-94 Opti mod: http://www.ls1tech.com/forums/lt1-lt...-94-folks.html
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