Question about 2002 Cadillac Sts

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92 Sts with 92000+. Chk engine lite on. Code P1860. Was told it's a TCC and PMW cyl. Again told we have to remove trans to fix. Costs range from $1000. to $3000. Help....Can it be by-passed? Not having ANY shifting problems.

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  • Chuck01642 Apr 11, 2011

    Where is the solenoid?

  • Chuck01642 Apr 15, 2011

    Un-sure of the answer. If you agree where is the solenoid located?

  • Chuck01642 Apr 15, 2011

    What a great answer to my question re. TCC solenoid problem. My only problem now is I live in a area that requires emissions and they won't test your car if "service engine light" is on. The way I got around it this year was to reset codes and drive around for 75 miles to re-establish codes. I'm sure you know if you drive real slow the light won't come on. I passed emissions! Next year I do the same thing again.

    Thanks again

  • Chuck01642 Apr 15, 2011

    Fantastic job. Just what the Doctor ordered.



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We see this all the time, in order to repair the problem you will have to remove the transmission, but you don't have to repair it, the car will still run just fine.

what the TCC is, is a lock up torque converter when the engine is over a certain temperature and the car is at cruse and not under any type of load, the on-board computer opes a passage inside the transmission that allowes fluid pressure to apply a lock up clutch inside the torque converter, what this does is make a solid direct link between the engine and transmission, witch will allow the engine to operate at a slightly lower RPM around 300 RPM and this will give you slightly better fuel mileage around 2 more miles to the gallon.

if you don't repair the problem the engine will run at a slightly higher RMP and get a little less fuel millage, but the car will run just fine.

this is a common problem and we see most owners not fix the problem and just ignore the light or cover it up.

so don't panic, you are just one of many who have this problem and although it would cost around $1,000-$1,400 to repair the problem, you don't have to repair if you don't want to.

Good luck, and let me know if there is any thing else you need.

Posted on Apr 15, 2011

  • john nail
    john nail Apr 15, 2011

    thats a good idea on the emision test, i was going to tell you to drive it in 2nd so the transmission would not try to engage the TCC.


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Replace the tcc solenoid only and see what happens, the trans stays in the car upon replacing that part. It maybe the only faulty part you have instead

Posted on Apr 09, 2011


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I have a 2001 aurora and code p1860 p1860 came up what is this and how much to fix

P1860 All GM - TCC (transmission Torque Converter Clutch) PWM Solenoid Circuit Electrical.
P1860 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 circuit 239. The Powertrain Control Module (PCM) controls the solenoid by providing a ground path on circuit 418. 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 is the code detected? 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.

Possible causes - Faulty Torque Converter Clutch Pulse Width Modulation (TCC PWM) Solenoid
- Torque Converter Clutch Pulse Width Modulation (TCC PWM) Solenoid harness is open or shorted
- Torque Converter Clutch Pulse Width Modulation (TCC PWM) Solenoid circuit poor electrical connection. Unless you have a factory manual and very good auto repair skills this is best left to an expert. It is a messy dirty job that requires removing the parts inside the transmission for testing..

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Found that code very easily on Google. Is is a transmission code in relation to the TCC (torque converter clutch). Could be a lack of maintenance, burnt fluid or debris in the fluid. Could also be a bad TCC solenoid or another internal trans issue. You will more than likely need to visit a qualified transmission repair facility unless you are good with trans internals.

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The code you provided "should" has P1860 warming appear on the scanner.

P1860 + P0073 are the codes for Torque Converter Clutch solenoid problem.
Top off the ATF to max.
Drive the car for 15 minutes and re-scan.

Make sure you get all the codes.

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Servise engine light on the code is p1860

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1999 chevy lumina 3.1 v6 code p1860

DTC P1860 is a type "A" DTC and indicates a torque converter clutch pulse width modulation solenoid electrical problem. When set it disables shift adapts and inhibits TCC functions such as the lock/unlock when in 4th-OD. Possible flaky TCC-PWM solenoid.
If you have a 4T65E the TCC-PWM solenoid is located under the side cover assembly. Not exactly easy to replace DIY. Engine/tranny has to be dropped down on the sub-frame assembly.

You could check the input voltage (12 volts) and ground/low to the solenoid via the main electrical connector. And check the resistance of the solenoid at the respective pins on the above connector. Not sure what the value is but you can get that from a transmission service shop or the dealer's manuel.

Assuming you have the 4T65E auto transaxle the 20 way electrical connector is located driver's side top. You should see it looking in. Gray connector and the only electrical plug going to the transmission. Twist counterclockwise. 

Other than checking the wire harness, and just an example once the solenoid is proven bad and replaced the local AAMCO charges around $500-$600 including the part but cost will vary depending on where you live. Good luck and sorry for the bad news. Keep me posted, be glad to help.

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1 Answer

Fault codes

DTC P1860 is set if PCM detects a continuous open or short to ground in the TCC PWM solenoid circuit.

If your inclinded to attempt to fix this yourself, I have some trouble shooting proceedures that you can use. They are very involved, and could require the trans oil pan to be removed to get access to the solenoid.

If your not up to that, take it in to get it fixed.

TCC PMW solenoid is used to control fluid flow acting on the converter clutch valve.
The Solenoid controls TCC apply and release.
The Solenoid is attached to the transmission valve body. To get to it you have to remove the tranmission oil pan. Changing it should be no problem.
But do you need to replace it? To determine that you have to figure out if it is the wiring that goes to the solenoid or if the solenoid itself is shot.

The PCM uses the TCC/PWM solenoid to control when the torque converter clutch applies and how soft or harsh the TCC apply feels to the customer. The TCC/PWM also controls the release feel of the torque converter clutch. "

Ignition voltage is supplied directly to the solenoid through a fused circuit. The Powertrain control module commands solenoid on or off by applying or removing the ground.

P0753 Shift Solenoid A Electrical P0758 Shift Solenoid B Electrical
Good luck and hope this helps

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GM service engine code P1870/2000 GMC Sonoma 2.2 cylinder

you jave a biggie here.
here is some info
The Powertrain Control Module (PCM) monitors the difference between engine speed and transmission output speed. In D3 drive range with the TCC engaged, the engine speed should closely match the transmission output speed. In D4 drive range, with the TCC engaged, the TCC slip speed should be -20 to +60 RPM .

When the PCM detects excessive TCC slip when the TCC should be engaged, then DTC P1870 sets. DTC P1870 is a type B DTC.

  • No TP sensor DTCs P0122 or P0123.
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  • No 2-3 SS valve DTC P0758.
  • No 3-2 SS valve assembly DTC P0785.
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  • The TFT is between 20-130°C (68-266°F) .
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