Need help with 3-2 downshift solenoid code 84
04-07-2011, 11:21 AM
#1
Need help with 3-2 downshift solenoid code 84 I'm competent with older TH350s and 400s, but completely new to the 4L60E, so that being said...
Car is a stock 94 Formula A4, intake & exhaust only, tuned by PCMforless for EGR delete, AIR delete, mild performance tweak- standard stuff. No other mods. This is a very recently rebuilt transmission, looks brand new inside.
Car is throwing Code 84 "3-2 downshift solenoid feedback fault." Maybe not knowing better, I replaced the 3-2 solenoid, but it came back after 4-5 cycles of KOEO, run & cleared 3 times with a scanner.
I did a bunch of research for testing the wiring harness, i.e. by pulling the black PCM connector and checking for continuity down to the case connector pin "S." As soon as I can get back to the car (22 mi. away) I'll check that. I can also check the harness inside for breaks/continuity to the solenoid connector, but it looked good when I was in there
Aside from looking for busted wires to or inside the transmission, is there anything else I need to know? Has anybody fixed this themselves and ended up tuning out the code as a last resort?
Car is a stock 94 Formula A4, intake & exhaust only, tuned by PCMforless for EGR delete, AIR delete, mild performance tweak- standard stuff. No other mods. This is a very recently rebuilt transmission, looks brand new inside.
Car is throwing Code 84 "3-2 downshift solenoid feedback fault." Maybe not knowing better, I replaced the 3-2 solenoid, but it came back after 4-5 cycles of KOEO, run & cleared 3 times with a scanner.
I did a bunch of research for testing the wiring harness, i.e. by pulling the black PCM connector and checking for continuity down to the case connector pin "S." As soon as I can get back to the car (22 mi. away) I'll check that. I can also check the harness inside for breaks/continuity to the solenoid connector, but it looked good when I was in there
Aside from looking for busted wires to or inside the transmission, is there anything else I need to know? Has anybody fixed this themselves and ended up tuning out the code as a last resort?
04-07-2011, 06:59 PM
#2
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Yes many 94's didnt even have a 3-2 shift solenoid. This would require you to change your valve body and the separator plate. I would bet that the 3-2 valve is sticky. Find a diagram of the valve body online and check it out. Make sure that the valve also hasnt wallowed out our valve body. If you have a nice scanner that does functional tests you can change the duty% of this solenoid as you drive get it it to down shift into second. It acts as you are changing the throttle. Im pretty positive you can still do that test with obd 1 but dont hold me too it.
04-27-2011, 09:52 AM
#4
I unplugged the case connector and threaded it back up to the top, disconnected the battery, PCM black connector. I checked the harness where it used to go behind the EGR pipe and though the corrugated sheath was a bit melted in one spot, there wasn't any damage to the wires. I wrapped it back up and put heat tape around it while it was out in the open.
Next I checked continuity for the ground and power between the case connector and the corresponding pins on the PCM's black connector. B13 to pin S on the case connector, B29 to pin E to find a voltage supply. Both had continuity, so the harness has no breaks between the trans and the PCM for the 3-2 circuit. So that points to either the harness inside the trans or problem with the PCM. I have a spare PCM I can send to Bryan at PCMFORLESS but I can't see a bad PCM being the problem. Harness inside the trans is available at O'Reilly for $55.00...
Other ideas, anyone?
Next I checked continuity for the ground and power between the case connector and the corresponding pins on the PCM's black connector. B13 to pin S on the case connector, B29 to pin E to find a voltage supply. Both had continuity, so the harness has no breaks between the trans and the PCM for the 3-2 circuit. So that points to either the harness inside the trans or problem with the PCM. I have a spare PCM I can send to Bryan at PCMFORLESS but I can't see a bad PCM being the problem. Harness inside the trans is available at O'Reilly for $55.00...
Other ideas, anyone?
05-09-2011, 11:30 AM
#5
Ok, so I've done some research and here's what's going on:
For the experts, this trans is a PWM version and has the 9-14 ohm solenoids in it, in a non-PWM PCM car. I was going to unplug the PWM solenoid and stake the bore in the TCC regulator/ apply next to the PWM, but the bore has a piston in it with 2 lands. All the documentation on the staking mod I've seen show a spring in the inner which you can spread with a pick, etc. to get the piston to move out of the bore. I can't get this one to move to the outside at all and I suspect I couldn't unless I removed the valve body and put in a piston that matches the one I've seen in the mod pics.
Anybody seen this before? Maybe this is because a 'fix' has been applied when it was rebuilt? Like that odd piston is part of a Sonnax kit, etc.? Should I be trying to stake that bore at all or leave it alone? I think the worst if I just left it as is with the PWM solenoid unplugged would be the loss of lockup and some extra heat, loss of gas mileage... but I want to fix it right and not lose lockup.
This started as a simple code 84 troubleshoot- replaced the 3-2 downshift solenoid and the code came back. Started doing some research and here I am. It looks like that if the PWM solenoid is connected to the harness and gets power in the presence of a non-PWM PCM wiring setup, it'll intermittently steal the voltage from the 3-2 solenoid and cause the code (circuit failure on the 3-2 downshift solenoid).
A pic of the TCC regulator/ apply- freaked when I saw the pic-thought that was a gouge in the land, but just fluid. 2nd pic is from a post on impalassforum.com showing the standard PWM stake mod:
For the experts, this trans is a PWM version and has the 9-14 ohm solenoids in it, in a non-PWM PCM car. I was going to unplug the PWM solenoid and stake the bore in the TCC regulator/ apply next to the PWM, but the bore has a piston in it with 2 lands. All the documentation on the staking mod I've seen show a spring in the inner which you can spread with a pick, etc. to get the piston to move out of the bore. I can't get this one to move to the outside at all and I suspect I couldn't unless I removed the valve body and put in a piston that matches the one I've seen in the mod pics.
Anybody seen this before? Maybe this is because a 'fix' has been applied when it was rebuilt? Like that odd piston is part of a Sonnax kit, etc.? Should I be trying to stake that bore at all or leave it alone? I think the worst if I just left it as is with the PWM solenoid unplugged would be the loss of lockup and some extra heat, loss of gas mileage... but I want to fix it right and not lose lockup.
This started as a simple code 84 troubleshoot- replaced the 3-2 downshift solenoid and the code came back. Started doing some research and here I am. It looks like that if the PWM solenoid is connected to the harness and gets power in the presence of a non-PWM PCM wiring setup, it'll intermittently steal the voltage from the 3-2 solenoid and cause the code (circuit failure on the 3-2 downshift solenoid).
A pic of the TCC regulator/ apply- freaked when I saw the pic-thought that was a gouge in the land, but just fluid. 2nd pic is from a post on impalassforum.com showing the standard PWM stake mod:
05-09-2011, 11:34 AM
#6
Couple more ideas, couple more questions:
If I go find a valve body for a 94 trans, what do I need to do to make it work on a trans that is apparently equipped with a PWM pump? I'll need a seperator plate, of course. Also new 1/4" check *****; what else? I'm betting if it'll work at all to mate a 94 valve body to a 95+ PWM-type pump equipped trans, I'll need to make some minor mods to the seperator plate (add a hole here, widen a hole there...).
Is the pump actually different between 94 & 95 or are the 95 & up marked PWM on the pump housing just for identification?
Hell, I'm thinking about having a transmission specialist do it but I'm having a hard time finding anyone that knows as much as I do about my problem and options as I do. Last thing I want to do is go educate somebody so they can do some labor and charge me a bunch of cash to do something I should have done in the first place. Problem is finding someone who can talk to me and give me accurate information on the early 4L60E and ensuing changes. So now I'm looking for comprehensive books on the 4L60E. Who knows- I may learn to work on transmissions from this. But I've always hated trans work and wanted nothing to do with it...
If I go find a valve body for a 94 trans, what do I need to do to make it work on a trans that is apparently equipped with a PWM pump? I'll need a seperator plate, of course. Also new 1/4" check *****; what else? I'm betting if it'll work at all to mate a 94 valve body to a 95+ PWM-type pump equipped trans, I'll need to make some minor mods to the seperator plate (add a hole here, widen a hole there...).
Is the pump actually different between 94 & 95 or are the 95 & up marked PWM on the pump housing just for identification?
Hell, I'm thinking about having a transmission specialist do it but I'm having a hard time finding anyone that knows as much as I do about my problem and options as I do. Last thing I want to do is go educate somebody so they can do some labor and charge me a bunch of cash to do something I should have done in the first place. Problem is finding someone who can talk to me and give me accurate information on the early 4L60E and ensuing changes. So now I'm looking for comprehensive books on the 4L60E. Who knows- I may learn to work on transmissions from this. But I've always hated trans work and wanted nothing to do with it...
05-09-2011, 09:00 PM
#7
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I think you have the 3-2 solenoid mixed up with the pwm tcc solenoid. All 4l60e transmissions up to 2008 have had a 3-2 solenoid. In 2009 this solenoid was removed from the valve body and there were some other changes made at this time. The tcc pwm solenoid was added in 1995 and is still being used today. However in 96 it was changed to another style with a different ohm value.
Gojira94 from what I can tell the issue you have here is you have the wrong internal wiring and also the fact that you have a pwm pump. Not sure about the separator plate at this point from what you have posted but the reason for the code I believe is because the computer is not seeing what it should with the 3-2 solenoid you have. I do not have the ohm values or schematic in front of me at the moment Also you should only have one solenoid and connector in the front portion of the valve body.
Depending on which 95 valve body you have you might be able to use it with the correct wiring, separator plate and pump. I would really have to see what you have to point you in the right direction. The difference in the two is in the 3-2 valve line up. The late style the valve can be removed with just removing the clip that keeps the solenoid in place and only has one spring. The early style has an end plug that is infront of the solenoid and has clip to keep it in place. It also has two springs in the valve lineup.
I believe that the computer could be fooled by installing the correct internal harness and solenoid. This is not how I would do it but you could try it. IMO when I build units I used what is supposed to be in there and not what might work if you know what I mean. Hope this helps. Vince
Gojira94 from what I can tell the issue you have here is you have the wrong internal wiring and also the fact that you have a pwm pump. Not sure about the separator plate at this point from what you have posted but the reason for the code I believe is because the computer is not seeing what it should with the 3-2 solenoid you have. I do not have the ohm values or schematic in front of me at the moment Also you should only have one solenoid and connector in the front portion of the valve body.
Depending on which 95 valve body you have you might be able to use it with the correct wiring, separator plate and pump. I would really have to see what you have to point you in the right direction. The difference in the two is in the 3-2 valve line up. The late style the valve can be removed with just removing the clip that keeps the solenoid in place and only has one spring. The early style has an end plug that is infront of the solenoid and has clip to keep it in place. It also has two springs in the valve lineup.
I believe that the computer could be fooled by installing the correct internal harness and solenoid. This is not how I would do it but you could try it. IMO when I build units I used what is supposed to be in there and not what might work if you know what I mean. Hope this helps. Vince
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05-10-2011, 11:28 AM
#8
Last night I just left the PWM solenoid disconnected, filled it and drove it. It shifts fine. I left my scanner at the house (the one time I take it out of the DD I forget to put it back in), so I can't see if the code 84 is still there. However, given that it shifts normally, I'd say it's no longer stuck in 3rd gear soft landing mode.
I think my biggest problem is the total loss of TC lockup with no way to put it back...
With a 2.73 rear gear, a stall 200 over stock and no TC lockup, it's a dog. But it drives and cruises for the moment. All 3 drain and fills I did while working it showed a lot of friction material in the fluid. I bet some minor damage is done already. So I'm shopping a dirt cheap early 4L60E in need of a rebuild and do it myself with a beefed up sunshell, etc. etc. etc.
I think my biggest problem is the total loss of TC lockup with no way to put it back...
With a 2.73 rear gear, a stall 200 over stock and no TC lockup, it's a dog. But it drives and cruises for the moment. All 3 drain and fills I did while working it showed a lot of friction material in the fluid. I bet some minor damage is done already. So I'm shopping a dirt cheap early 4L60E in need of a rebuild and do it myself with a beefed up sunshell, etc. etc. etc.
