01 C5 ZO6 NEED HELP!!!!

by James Zompetti
(Seattle, Washington)

My car is in the "Reduced engine power mode" I've pulled all the codes from the onboard diagnostics. P1120HC, P1220HC, P1515H, P1516HC, P1518HC, C1214HC, C1278H, C1295H. I've had problems with the traction control for quite some time now. Basically, it hasn't worked since I've had the car. It went into "reduced engine power mode" after a hard acceleration from 1st to 2nd. I've been doing a lot of research and work on it. I've replaced the battery. Pulled the throttle assembly off. Took it apart and cleaned it. Checked all my spark plugs and wires. I've cleaned some of the chassis grounds. Replaced the tps sensor. Pulled the RF fender off and inspected the PCM and the TAC module. Everything is clean and secure. There were no loose wires or plugs. The only thing that I have noticed is the TAC module rattles. There is something loose inside of it. Is This Normal? I've been to a few dealerships now and none of them were willing to offer any advice or help of any sort. No wonder GM is looking for bailout money. No customer service skills whatsoever! I'm at a complete loss on what to do.

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Jun 30, 2009
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The solution!
by: Corvette-web-central

Here is the path to the fix!

Chris, Finally my car is running. It turns out it was a bad servo-motor. Once
again thanks for all your help. Maybe you can post this now for others
experiencing similar issues as I was. Once again thanks for your help and
sparing me from the overpriced dearlership. James

--- On Thu, 5/7/09, corvett2@corvette-web-central.com
wrote:

From: corvett2@corvette-web-central.com
Subject: Re: This may help also!
To: "james zompetti"
Date: Thursday, May 7, 2009, 9:57 PM

Looks like the TAC module sends 8.0v to the Acuator via 2 circuts. With the
key on engine not running you could check for the Voltage. Control #1 is
the yellow wire and Control #2 is the brown. They should be the same value
for resistance. Take your lead and check the yellow and brown (on the TB
side) together first to check for a short between #1 and #2 circuts. Next
check them individually with one lead at a time on the yellow or brown wire
and the other lead to the body of the TB. I can run out and check my car so
we can compare the values of the Acuator circuts at the TB. I know how
frustrating this is hang in there we will get it. I know how it is to not
want to take a car like ours to the stealership!

james zompetti writes:

> Update. I've pulled the servo-motor off the throttle body. I tried running a direct lead strait to the battery to see if it would work. Nothing happened. Upon closer inspection I noticed the motor smells like an electrical burn. Do you know if there is another way to test this part off the car?
>
> --- On Thu, 5/7/09, corvett2@corvette-web-central.com wrote:
>
> From: corvett2@corvette-web-central.com
> Subject: Re: This may help also!
> To: "james zompetti"
> Date: Thursday, May 7, 2009, 11:21 AM
>
> I think we have to validate everything is working as we go. I m glad you
> have a scan tool what kind is it? I have Auto-tap. Do you know someone
> with a C5 you can swap in their Servo motor or whole TB? Which relays are
> you concerned with? It sounds like the servo motor is not working for what
> ever reason. I m not sure in the scan tool if you are seeing the TP sensor
> or the servo position. My guess is that its the TP sensor. As far as a
> suggestion for a TB I cant really tell you. Since you have Magnuson S/C I m
> not sure what will adapt to it. You could look into a ported TB but they
> usually make you reuse your Acuator motor. An LS2 90mm may work but you
> would need an adapter harness and an adapter to your S/C probably. You
> could try and find one on ebay that is stock and if it doesn't work just
> relist just sell it.
>

Apr 25, 2009
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TAC MODULE
by: Anonymous

Your the second person that told me I should look at the TAC module. I'll have to order a new one. Hopefully they don't cost an arm and a leg. I have read about some other guys having problems with their fuel pumps as well. I don't think that's the case with mine since it was replaced with a high volume one to compensate for the supercharger. I guess there's always the chance it's defective. Thanks for the feedback and your time. You Guys have been great!!!! James

Apr 25, 2009
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lost power
by: HIT_N_RUN 86

James, I would try a different tac module first but I had this problem on my on my c4 and found out it was the fuel pump not sending enough fuel to the engine. This made the pcm think I was running low on fuel and put it in survival mode to get to a gas station. Changed the pump and it fixed it. But in your case with the high rpms between 1st and 2nd you might need to have your pcm put on a tech 2 dianostics and reprogram the pcm. It sounds like to many rpms stopped the motor from blowing up its a saftey feature. Good luck! Not saying that would've happened but GM put that feature in so people didn't sit with their foot mashed on the gas and get a new engine.

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