[trotter8]

I have been having this problem since about January. The progression usually goes as follows. The car will behave perfectly fine most of the time, then implode. First the transmission will begin to shift very hard, then the idle RPM's will be way too high (spec is 650, I will get around 1100), sometimes the center stereo screen will show "Service Idle Control", then any short amount of time later the center stereo screen will show "Reduced Engine Power" and the car will basically cut all gas except enough to keep the engine idle. This will happen at any type of driving whether stopped at a stop light or going 70 on the interstate (which really sucks).

I have recently found that I can temporarily fix the problem by pressing F1 and F6 on the stereo to enter the diagnostic center and quickly hit "Clear All Codes". As soon as the codes clear, my fuel comes back online. It is the craziest thing that I am able to do this while going 70 on the interstate. I have taken the car in numerous times to the dealership and all they can do is reprogram the computer which will fix it for a short time. Last time they told me to replace the throttle body and I am desperate so I did. This actually seemed to increase the frequency of the problem.

Unfortunately there were more error codes on the computer, but I cleared them to get my fuel to come back. At the moment it is only showing two error codes:

U1000H
P07000

This problem is killing me and I appreciate any help people are willing to offer.

[trotter8]

After a number of attempts at fixing the problem (replacing transmission control module and the throttle body, as well as cleaning many wire connections) the one that finally seems to have resolved the problem was the wiring harness leading into the throttle body. It appeared that the previous owner of the car had already replaced this so I wasn't thinking it would need to be replaced again. But it appears that is what solved the problem (fingers crossed).

[Texas Jim]

After a number of attempts at fixing the problem (replacing transmission control module and the throttle body, as well as cleaning many wire connections) the one that finally seems to have resolved the problem was the wiring harness leading into the throttle body. It appeared that the previous owner of the car had already replaced this so I wasn't thinking it would need to be replaced again. But it appears that is what solved the problem (fingers crossed).

Sorry I was not able to help you with your problem, but I will Thank You for the follow up post.
It may very well help someone else that has a similar problem.

[bobthebuilder]

I have the exact same problem on my car, it was a salvage title and the wiring harness is all messed up. I didn't know you could clear out the code when it went to engine reduced on the highway, luckily each time it happened, I was able to get to the service road. The main problem with my wiring harness is the PCM connection, It really comes down to a orange and blue wire a the end, somehow in the wreck, it was previously in, the wires were damaged all the way to the terminal, I waiting on the new metripack gm terminals to get in but in the mean time, I'm using terminals from a different wiring harness the owner gave me. The the terminals from the other wiring harness are too big, so I've had to put smaller gold 20 gauge terminals inside the bigger terminals, but, because they don't lock in, they slip out every couple of days and I have to keep pushing them in. Also, the wire that went to the throttle body was grinding against the edge of a pulley, I had to tape it the the radiator hose but I think the damage was minimal.

There are also some other wires missing on the car I have no idea where they go. I just found out a vacuum line was missing that went all the way to the back of the manifold, I had that replaced yesterday.

Wiring to PCM



Wire to Throttle Body



Unknown connection by ac unit



Unknown connection by washer fluid



Unknown connection by washer fluid, further down



Unknown connection by front passenger side tire