P1860

[BoiseGTP]

1999 Buick Regal GS turbocharged. Built transmission has a fresh rebuild, has a brand new 3500 TC, and I have tested the solenoids and wiring and seems all good. Slips in 3rd pretty bad.

Any ideas? I will try a new PCM this weekend when I get my offboard back.

 

[Fivefingerdeathpunch]

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.
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A different computer shouldn't change this.

 

[BoiseGTP]

A different computer shouldn't change this.

It might not but a PCM does go bad once in a while. Running out of things to check and I have a spare PCM sitting around. It's a new solenoid and I tested it, I had all the wires unbound and checked them for shorts and tested from PCM to the trans. I have changed the TCC duty cycle to max 100 and min 55.

Is there anything hydraulic that can cause this?

 

[Fivefingerdeathpunch]

That I don't know.

Have you tried changing the TCC settings back and seeing if the issue went away? I'm just throwing out guess here, I've never changed major transmission settings when tuning a 3800.