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P1860

Tiny
XJSHEN
  • MEMBER
  • 1998 CHEVROLET LUMINA
  • 3.1L
  • V6
  • FWD
  • AUTOMATIC
  • 220,000 MILES
At inspection station crealted code p1860. Before go to station I detected code with auto scanner Actron CP9575, and no any code found. But after after tech insert inspection instrument box onto car during inspection created Service Engine Soon ligh with code p1860. While all inspection sheet value indicated exactly same as last year's normal inspection results.
After clear the code with my autoscanner I have run for one week 150 miles there was no any code found, and I went to the shop and the same tech Tech created the Service Engine Soon ligh with code p1860.
It is absolutely not due to machenical problem but due to either one of :
The PCM commands the solenoid ON (90%) and the voltage feedback remains high (B+). Or voltage feedback remains low (0 volt).
How to check the cause and fix it?
Thanks for your instruction and help!
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Saturday, January 23rd, 2016 AT 11:00 PM

15 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Your scanner will not pick up this code. It is a transmission code and is either a short in the power width modulated solenoid. It can be either a short in wiring, a bad pcm, or tcc or something similar a local pro will have to fix this.
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Sunday, January 24th, 2016 AT 8:31 AM
Tiny
XJSHEN
  • MEMBER
  • 218 POSTS
Thanks! My scanner can pickup the p1860 code. Before go to the shop I detected no any code, but in the shop after connected inspection box for the work in side car, the same warning light and the code was created, and happend twice after one week past.
There is only short in wire that possi ly caused the error code, and there was no chance to cause bad PCM or bad TCC at seat during the inspection time where tech was sit in the seat. If TCC or PCM was bad, after clear the code the error code would appear again, but my car did not appear during one week 150mi driving.
How to check fix short in wire? If my assumption is true, after clear the code and run OBD ll warmup cycle, there would be no more error code appear if no short in wire happen in normal case.
Is it right?
How much will be cost to fix the error?
Thanks for your professional detail instructions!
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Sunday, January 24th, 2016 AT 5:44 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Icouldn't even begin with a cost as shorts are hard tofind sometimes other times not it can be in the trans a solenoid or torque converter clutch.
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Monday, January 25th, 2016 AT 7:15 AM
Tiny
XJSHEN
  • MEMBER
  • 218 POSTS
How to check short ground in wire caused p1860? And short in PCM TCC cercuit caused p1860?
You have been never replied to any question right so far.
Thanks!
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Monday, January 25th, 2016 AT 7:53 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Majority of people willnot attempt this. See pics.
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Monday, January 25th, 2016 AT 8:10 AM
Tiny
XJSHEN
  • MEMBER
  • 218 POSTS
Great and thanks!
Dwhere is the 7-pin con-terminal located on the car? I'll check them following the manual.
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Monday, January 25th, 2016 AT 9:09 AM
Tiny
HMAC300
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  • 48,601 POSTS
At the transmission
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Monday, January 25th, 2016 AT 9:25 AM
Tiny
XJSHEN
  • MEMBER
  • 218 POSTS
Do I need open the transmission box?
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Monday, January 25th, 2016 AT 1:30 PM
Tiny
HMAC300
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  • 48,601 POSTS
Wiring plug will be in area where arrows are showing. I have no further comments or suggestions
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Monday, January 25th, 2016 AT 3:16 PM
Tiny
XJSHEN
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Thanks a lot!
I will find video.
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Monday, January 25th, 2016 AT 10:37 PM
Tiny
XJSHEN
  • MEMBER
  • 218 POSTS
Where is PCM C2 connector location location on the car? Where is p1860 code related circuits included: circuit no. 418, pin 78 (BRN), TCC PWM Solenoid Control; circuit no. 657, pin 63 (YEL ) TCC Release Switch Signal.
May you share DTC P1860 TCC PWM Solenoid Circuit Electrical 3.1L diagram?
Thanks!
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Tuesday, January 26th, 2016 AT 7:55 AM
Tiny
HMAC300
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The pcm has two connectors just look for the the numbers as they are on the connector. It'son the front right strut tower I have nothing more to give you.
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Tuesday, January 26th, 2016 AT 9:26 AM
Tiny
XJSHEN
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Thanks! What I am lookinf for is location of the connector, in the hood, where is located. I analysed available mistake happened during Tech's work of connect inspection box where many wire connectors located. I looked around the connector seat where many wires in diferent color were connected to. I opended front cover of driver's side and found the connector. It may be shorted in ground. Connector onpull or push or wrong insert the scan connector all may cause ground short of wire to TCC solenoid.
Is it right?
Thanks!
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Tuesday, January 26th, 2016 AT 2:08 PM
Tiny
XJSHEN
  • MEMBER
  • 218 POSTS
Second time inspection cleated service engine soon light with three code, p1860m p1350, and p1870. When connect the instrument box outside of shop there was no any signals, but after finish and tech pulled out the inspection connector the service engine soon light cameup with three codes.
Can you explain the differences of lights with different code?
Thanks!
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Tuesday, January 26th, 2016 AT 2:15 PM
Tiny
HMAC300
  • MECHANIC
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Nope and there will be no further replys
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Tuesday, January 26th, 2016 AT 3:04 PM

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