Vortec help

[baloo]

Hey I have been gone a while and I am back with a new name, my old computer and server and electric goop went south, so I am starting over. Thanks for the great site. Now to my newest problem: I have a 4L60E with the check engine light on, the code is P1860. The engine runs great and the only thing I see is the torque convert does not seem to be locking up, and the trany is about 200 degrees not the usual 170-180. Any help would be great, I gonig to pull the pan and start looking. JL

 

[hj60]

That's the code for an electrical problem in the TCC solenoid circuit.
Could be a bad ground.

P1860 TCC PWM Solenoid Circuit Electrical

 

[baloo]

THanks for the reply. A bad ground inside the trany? or outside? Any clue as how to find the bad ground. Auto transmissions are magic (black) to me and the wires are not helping. Could it bea bad wire to the PCM if so which plug runs the trany? Thanks for your help and time.

 

[hj60]

The TCC solenoid most likely grounds to the case of the tranny. Might be a good idea to go
get one of those generic braided ground straps and provide a solid ground from the tranny to
the frame or body.
As far as where to look for the problem in your case, you'll need to get a good wiring diagram
for the Vortec/4L60E. Then just start tracing wires.

 

[baloo]

Thanks again I worked on wires last night and the problem went away, unitl today. When the Cruiser has run for about 30min the fault shows agian, I let it sit for 2 hrs and cool down , I cleared the fualt and all was well for about 20 min of driving then it faulted again, seems to be temp related but the trany and engine are reading normal until the fualt. I'll try a new pressure switch and ground strap tonight, the trany shop thinks it is the flluid pressure switch or low fluid levels despite what the dip stick says? Let you know what happens maybe it will help some one else.

 

[hj60]

If it's temperature related, check your trans fluid temp sensor. It's one of the 8.5 million inputs
the PCM uses to determine TCC lockup.
If you just pulled a 4L60E out of a pickup, it may be wise to invest in all new sensors for it.
The input shaft speed sensor can test good, but actually be malfunctioning at highway
speeds.

 

[baloo]

Okay I gave up and it went to the real trany shop. They are still looking for the problem they think it is a wire or a bad PCM. They are leaning to the wire they said they read about a bad crimp from a survice alert. ANy body ever seen this problem.

 

[orangefj45]

there is no input speed sensor on a 4l60e.
sounds to me like the internal harness might be bad, pretty common problem. they end up leaking along the wires right into the "case connector" and then the signal shorts out. does'nt sound like anything major.

 

[orangefj45]

are you sure the trans-engine-computer are all the same year? the 4l60e has had 3 electrical design changes so far and you can not interchange them.
93-94 5 solenoid design
95-96 6 solenoid design, non-pwm
96 and up 6 solenoid design with pwm (pulse width modulation aka modulated lockup)
and then in 2000 they changed case design, but same electrical until 2003................

 

[baloo]

It is a 1999 4L60E the PCM was areplacement from the folks that programed it, BTB. The 1st PCM did something even GM said was impossible but it happened and they quickly replaced it. The word now is a bad board in the PCM or a bad crimp in the wires outside of the trany.. I'll lkeep you posted so hopefully no one else will have this fight.

 

[baloo]

Well the trany shop thinks it is a bad crimp/wire so we built a jumper wire from the red terminal pin 7 to the trany and all seems well. I'll try it for about a month before I say it is fixed.