Throttle body tac motor

GMTECH01

MEMBER
2006 ISUZU ASCENDER
5.3L
V8
4WD
AUTOMATIC
190,000 MILES

I am a retired GM world class tech.
I replaced the tac motor connector after an engine overhaul and had no problems for six months. Then I got a p2135 and p1516. I diagnosed a bad throttle body tac motor and replaced it with a re-manufactured rockauto unit. Six months later same codes. So I warrantied the tac body. Six month later same codes. So I refreshed the PCM per a bulletin. Didn't fix it. So I replaced the throttle body with a new GM tac unit. Six months later only the p2135 came back with reduced engine power. I found another bulletin to replace the PCM if within the Julian build date but wondered if anybody has run into this. Once I had to rewire the tac throttle pedal pos. Sensor to the PCM as per GM tac engineer. Curious what anyone thinks. Haven't replaced PCM yet or even checked the Julian date because I don't think that's it.

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
47,536 POSTS

Definitely a correlation issue. did you replace the throttle pedal position sensor as well? Here are the wiring diagrams and a guide to help others that come to this post so you can test the connections. If it has good wiring and the sensor is new the only thing left is the PCM. Throttle bore is nice and clean right?

https://www.2carpros.com/articles/how-to-check-wiring

Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.

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