Wits end with 1996 Jimmy

I have a 1996 GMC Jimmy 4.3l 4wd with a 3 speed w/overdrive tranny. It all started with the shift solenoid going out so I have both shift soleniod's replaced and had the filter changed at the same time. One week after getting the jimmy back from the tranny shop the transmission manifold went out in it. So agian it went back to the tranny shop. After only a day of having it back from the tranny shop it tossed another transmisson code P1860. Now I am an ASE Cetified Mechanic but I dont know enough about trannys to save my life. The transmission shifts up and down ok (1st to 2nd seems a little hard) and has all the gears. But I dont know if this is maybe a sign that the transmission is about to go BOOM or not. And of course the local tranny shop that has worked on it twice already refuses to help any in this matter. What does this code mean and what can be done about it?

Give this a read:

http://www.hotrodders.com/forum/tcc-error-code-p1860-4l60e-tranny-62737.html

I wouldn't be surprised if you need an overhaul once it is fully diagnosed.

Well This is already starting to look like a bad sign to me that the trannys about to go out. After reading the other post it seems to me that all I can do with this problem is to fully rebuild the transmission to ensure that it stops throwing codes for the tranny all the time. Crap not good :banghead:

Code is for a PW lockup solenoid problem or wiring circuit to it.
Aso wiring inside and outside of transmission and wiring plug and to computer.
Any fluid in wiring plugin on transmission?
Not end of the world for a transmission bad transmission.
Needs some proper testing on wiring and solenoid.
Any other codes.
96 also had a computer wiring repair kit for the computers for bad ground covered by a TSB..

Code is for a PW lockup solenoid problem or wiring circuit to it.
Aso wiring inside and outside of transmission and wiring plug and to computer.
Any fluid in wiring plugin on transmission?
Not end of the world for a transmission bad transmission.
Needs some proper testing on wiring and solenoid.
Any other codes.
96 also had a computer wiring repair kit for the computers for bad ground covered by a TSB..


That is the only code that the computer is setting. and none are ready to be set. So the wireing harness from the ECM may have tranny fluid in it? Is that what your saying and do you know what TSB it was for the wiring harness kit?

That is the only code that the computer is setting. and none are ready to be set. So the wireing harness from the ECM may have tranny fluid in it? Is that what your saying and do you know what TSB it was for the wiring harness kit?

More bad open or shorted wiring but fluid in the wiring plugin is not good.
The tsb was for a wiring kit that repaired a ground wire problem to transmission computer.
I will see if i can find tsb .
All data or gm should have the tsb and details on it.

If manf date was feb 14 06 or later and it has the 1624421 computer it does not need the gn 12167310 wiring kit.
Kit was for older vcm before feb 14 06

Was the valve body replaced?

Baisiclly, the PCM is commanding the TCC PWM to apply, its not getting the proper response, its freezing shift adapts(your hard(er) shifting). Usually, but not always, usually though if you had a bad convertor clutch, it would also set a P1870 too.

The P1860 is as follows
Circuit Description

The torque converter clutch pulse width modulation (TCC PWM) solenoid valve controls the fluid acting on the converter clutch valve. The converter clutch valve controls the TCC application and release. The solenoid attaches to the control valve body within the transmission. The solenoid receives ignition voltage through the power feed circuit. The powertrain control module (PCM) controls the solenoid by providing a ground path on the control circuit. Current flows through the solenoid coil according to the duty cycle (percentage of ON and OFF time). The TCC PWM solenoid valve provides a smooth engagement of the torque converter clutch by operating during a duty cycle percent of ON time.
When the PCM detects a continuous open, short to ground or short to power in the TCC PWM solenoid valve circuit, then DTC P1860 sets. DTC P1860 is a type B DTC.
Conditions for Running the DTC


The system voltage is 10-18 volts.
The engine speed is greater than 450 RPM for 5 seconds.
The engine is not in fuel cutoff.
The PCM commands first gear.
The TCC duty cycle is less than 10 percent or greater than 90 percent.
Conditions for Setting the DTC

DTC P1860 sets if one of the following conditions occurs for 5 seconds:
Condition 1
The PCM commands the solenoid ON (90 percent) and the voltage feedback remains high (B+).
Condition 2
The PCM commands the solenoid OFF (0 percent) and the voltage feedback remains low (0 volt).
Action Taken When the DTC Sets


The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
The PCM inhibits TCC engagement.
The PCM inhibits 4th gear if the transmission is in hot mode.
The PCM freezes shift adapts from being updated.
The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
The PCM stores DTC P1860 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.
Conditions for Clearing the MIL/DTC


The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
A scan tool can clear the MIL/DTC.
The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
The PCM cancels the DTC default actions when the fault no longer exists and/or the ignition switch is OFF long enough in order to power down the PCM.
<A name=ss2-645366>Test Description


The numbers below refer to the step numbers on the diagnostic table.
<LI value=4><A name=ss1-645366>This step tests for voltage to the solenoid.
<LI value=5><A name=ss1-645366>This step tests the ability of the PCM and wiring to control the ground circuit.
<A name=ss1-645366>This step tests the resistance of the TCC PWM solenoid valve and the automatic transmission (AT) wiring harness assembly.

If manf date was feb 14 06 or later and it has the 1624421 computer it does not need the gn 12167310 wiring kit.
Kit was for older vcm before feb 14 06



The manufacure date of this jimmy was 10/95 so I will try to look into to see if this jimmy has ever had the wiring harness replaced. I will get back to you once I know.

Was the valve body replaced?

Baisiclly, the PCM is commanding the TCC PWM to apply, its not getting the proper response, its freezing shift adapts(your hard(er) shifting). Usually, but not always, usually though if you had a bad convertor clutch, it would also set a P1870 too.

The P1860 is as follows
Circuit Description

The torque converter clutch pulse width modulation (TCC PWM) solenoid valve controls the fluid acting on the converter clutch valve. The converter clutch valve controls the TCC application and release. The solenoid attaches to the control valve body within the transmission. The solenoid receives ignition voltage through the power feed circuit. The powertrain control module (PCM) controls the solenoid by providing a ground path on the control circuit. Current flows through the solenoid coil according to the duty cycle (percentage of ON and OFF time). The TCC PWM solenoid valve provides a smooth engagement of the torque converter clutch by operating during a duty cycle percent of ON time.
When the PCM detects a continuous open, short to ground or short to power in the TCC PWM solenoid valve circuit, then DTC P1860 sets. DTC P1860 is a type B DTC.
Conditions for Running the DTC


The system voltage is 10-18 volts.
The engine speed is greater than 450 RPM for 5 seconds.
The engine is not in fuel cutoff.
The PCM commands first gear.
The TCC duty cycle is less than 10 percent or greater than 90 percent.
Conditions for Setting the DTC

DTC P1860 sets if one of the following conditions occurs for 5 seconds:
Condition 1
The PCM commands the solenoid ON (90 percent) and the voltage feedback remains high (B+).
Condition 2
The PCM commands the solenoid OFF (0 percent) and the voltage feedback remains low (0 volt).
Action Taken When the DTC Sets


The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
The PCM inhibits TCC engagement.
The PCM inhibits 4th gear if the transmission is in hot mode.
The PCM freezes shift adapts from being updated.
The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
The PCM stores DTC P1860 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.
Conditions for Clearing the MIL/DTC


The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
A scan tool can clear the MIL/DTC.
The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
The PCM cancels the DTC default actions when the fault no longer exists and/or the ignition switch is OFF long enough in order to power down the PCM.
<A name=ss2-645366>Test Description



The numbers below refer to the step numbers on the diagnostic table.
<LI value=4><A name=ss1-645366>This step tests for voltage to the solenoid.
<LI value=5><A name=ss1-645366>This step tests the ability of the PCM and wiring to control the ground circuit.
<A name=ss1-645366>This step tests the resistance of the TCC PWM solenoid valve and the automatic transmission (AT) wiring harness assembly.







DTC code 1870 had shown up one week earlier (before this one). I had the local tranny shop look into it and they went ahead and replaced the transmission manifold (as they call it). Once the manifold was replaced is when this code started. The valve body as far as I know has never been replaced it has been removed twice, once to install both of the shift solenoids and once to install the transmission manifold.

I am not getting what manifold you are describing. The valve body is sometimes called the manifold, so I am assuming your talking about the same thing. If you were getting the P1870, I assume the valve body was removed to try and correct the P1870 by installing either a trans go kit or a sonnax TCC rebored regulator. At this point the P1870 will not show up until the P1860 is solved, becasue no TCC lockup is occuring as a result of the P1860. Check connections at the PWM solonoid, check for proper voltage, if that checks out, replace the solonoid. That should solve the P1860 code. After that, if the valve body was the P1870 problem, then hopefully at this point, you won't get that code again and you should be good to go. On the other hand if P1870 pops up again, and the valve body was corrected, then your problem is your convertor clutch.

I am not getting what manifold you are describing. The valve body is sometimes called the manifold, so I am assuming your talking about the same thing. If you were getting the P1870, I assume the valve body was removed to try and correct the P1870 by installing either a trans go kit or a sonnax TCC rebored regulator. At this point the P1870 will not show up until the P1860 is solved, becasue no TCC lockup is occuring as a result of the P1860. Check connections at the PWM solonoid, check for proper voltage, if that checks out, replace the solonoid. That should solve the P1860 code. After that, if the valve body was the P1870 problem, then hopefully at this point, you won't get that code again and you should be good to go. On the other hand if P1870 pops up again, and the valve body was corrected, then your problem is your convertor clutch.


Is the Torque Converter Clutch Lock-Up Solenoid the same as the TCC if so then I know right where to look. Or is it a differant pieace? But the "Transmission Manifold" that they replaced was a black (in color) unit that had 5 holes for the shift points anlong with a slim flat connector. Is that the valve body or is it somthing else?

Sorry guys I'm not much of a transmission mechanic I main deal with engines, 4wd and suspension.

That black box/manifiod is the TR switch / transmission range pressure switch assembley.

The 1870 code for compoment slipping is your main problem.
Can be caused by several things.
And one thing the computer ground deal wiring kit is for.
or other bad wiring.
or shift solenoids.
or TCC PWM solenoid .
or internal damage.
Or even a miss fire.


If it can not be fixed by the wiring kit and elctronic's and wiring to transmission.
Your problem is internal transmission.

There is several TSB"s and repair flow charts and test for the 1870 code.

But many times it is cause by internal pressure leakage and damage internal in transmission.

It needs to be put on a good transmission scanner by a good transmission diagnostic person to see if they can spot if it has actual slippage and where and how much the slippage is.

Many try to fix the code it with the valve body.
But it is usually only a band aid on real problem.
Here is Some info from a good old transmission man.,
In a nutshell, the valve body does chronically wear in the 4L60E especially in the lockup PWM bore. The code lights when there is more then 100 rpm or so when locked up. Depending on mileage and fluid condition will determine the next course of action. The seal on the input shaft gets tons of heat and is the most critical seal in the trans. If there are high miles, usually what it takes to wear the vb, then the rubber seals as well as the Teflon ones are just as worn. The 1870 code is telling me there is a internal leak in this trans...someplace. The transmission is a multitude of leaks and it is engineered that way, some are good leaks because they lube planetaries and some are not so good because they make the pump work harder to make up for the leaks inside. Teflon rings leak to get enough holding power to not leak. The point here is if you have excessive or extra leaks then the PWM must cycle higher pressure and volumes to compensate making it work harder and the very forces that wear out the vb bore are increased wearing the bore quicker. In addition to that factor, with internal leaks you also have increased temperature and heat kills big time in a tranny plus it decays the additives in the fluid itself and now you are in a downhill spiral as the trans self destructs form leaks and heat and destruction of the fluid itself. Now the hard parts will start to wear at an increased speed, the pump is trying to maintain for the fluid loss(leaks), the planets will start overheating as the bushings wear out you generate more hemorrhaging and more damage.
* Yes, at that point the vb is a bandaid, it may solve the problem for now but the internal wear and hardening of the seals is still there and will continue to wear. The problem I have with just throwing a vb at this problem is simply, the worn components will make the new vb work harder and cycle more than it should and the consequence of that is another prematurely worn out vb and ultimately overhaul of the trans that you should have taken care of before. The transmission is a complete and interdependent unit meaning all parts rely and interact on each other. If one part is worn out then you must deal with the unit on the whole. There are exceptions to every rule and the jeep is a good one, the accumulator plate is held down by too few screws and the plate is under enough pressure that when the screws break, the plate peels back like a lid on a dog food can. If caught soon enough then a repair of the valve body is sufficient to be a complete repair. If you have a 4L60E with 100k on it and smokey fluid and only a P1870 then you are not doing the customer a service by simply replacing the vb.
I have yet to take a trans apart that was simply coding 1870 and not found hard seals or other problems internally. Most of the time, I have not even needed to deal with the vb at all, aside from basic clean up and solenoid replacements. I have had to replace more transfer plates than valve bodies from the balls eating through. In the past 6 months, I have only replace 2 valve bodies.

Well I bought this Jimmy a month ago for my girlfriend, that is in love with it, and I have no clue about the prior history of it. All I can say is that I have had all these tranny problems with it and the engine and 4wd are perfect at 146k miles on it. So if the tranny seems to be in that kinda of shape it seems smart of me to just put a rebuilt tranny in its place and do away with all the problems together.

Yes if proper testing shows any slippage or pressure lose inside transmission.
Valve body or valve body kit would only be a band aid on it.
Let us know how it goes.
Good luck

Its a tough call..... I am of the crowd that prefers to try to save it rather than give up on it and rebuild it. Now if it needs a rebuild, then sure, there is no other choice. And if it is to be rebuild, I always perfer to upgrade internals rather than build to OE spec. I have rebuilt a few of these myself and have done quite a few with the valve body correction and I have had very few not work properly after the valve body correction. I also perfer the sonnax reamer correction rather then the transgo kit. Usually, the valve body correction didn't work because the vehicle was run too long with the worn valve body. The electronic trannies are not as forgiving as the older 400's or 700R4's were, they simply need proper hydraulic pressure to shift properly and lock up properly.

That said, a good bi-directional scanner and a person who knows what to look for can usually diagnose these trannies without to much trouble.

I think they in fact replaced the EPC solonoid (electronic pressure control solonoid) as you are describing it with the slim flat connector at the back of it. The solonoid is cylindrical and is black...that sounds like the EPC solonoid. Now if its coming up with the 1860 right after that solonoid was replaced, then it would be wise to try and correct that problem before giving up on it. They might have damaged the PWM solonoid or forgot to connect it again, or whatever....You need to pull the pan and inspect it and see what things look like in there.

Here is a good video on youtube on an older 4l60e, the internals are all the same all the way up to 2002 model year.
http://www.youtube.com/watch?v=6Svl0fDl1qI&fmt=18
Take a look at this and you'll have a better idea of what is what.