Dnealy

Hey guys, Ive got a couple things I've go to get taken care of with the z06 but now its in reduced engine power mode. I am pretty sure I have a bad TB, BUT I'm gonna post all the codes i just pulled out. Its a bunch because I just got done putting the whole top end back on. Car has a fully charged battery, and when I disconnected the rack from the steering wheel i "tied" the wheel off inside the cab so it would not rotate. Just wanted to throw that out there because i know that throws the dreaded Steering wheel position sensor code, Im about to replace that sensor this weekend anyways because i do have that code but its just a bad sensor this time . If anyone can think of anything that would throw it into limp mode let me know please. Its been doing it for a couple days now, i would shut the car off, wait a few seconds and go on my way. Last night I was going up the highway here, got on the gas id say maybe 30 % and boom, reduced engine power mode.

Codes-
Pcm TCS
P0134 H C U1307 H
P0154 H C C1214 H
P0530 H C C1278 H C
P0650 H C1286 H
P0801 H C C1287 H C
P0803 H C C1288 H
P1120 H
P1220 H C
P1221 H C
P1515 H
P1516 H

I checked all grounds, everything. Cleared all the codes, fired the car up and then got,

PCM TCS
P0803 C1278
P1220 C1287
P1221

Thanks for all the help guys

dgrant3830

P0803 1-4 Upshift Solenoid Control Circuit (M/T)
P1220 TP Sensor 2 Circuit
P1221 TP Sensors 1, 2 Performance
C1278 TCS Temporarily Inhibited By PCM
C1287 Steering Sensor Rate Malfunction

So, it looks like the throttle position sensor is having issues which is what tagged the C1278 code.

Dnealy

The shift solenoids i am in the process of fixing (have to find the plug since the place that did my first clutch messed them up, Long story) so you think its the sensor on the pedal or the one incased in the TB.

dgrant3830

I'm sorry....had an attack of stupidity on my part. It was not the throttle position sensor, rather Tire Pressure sensor. Sorry I sent you in the wrong direction. I'm not perfect.

All of those codes except the 803, will cause the TCS to shutdown the active handling system if equipped and cause problems for the TCS.

RogerZ06

Your problem is the SWPS. It can bug out and make reduced engine problem.

I had same problem but I ignored swps by turning traction control and active handling off.

When it gets bad enough. It will make dash go crazy and lose communication with BCM and PCM ETC...

I guess 2001 Z06 it messes with ground communication wire.

Dnealy

Im about to go pick up another 90mm TB from my buddy who's in middle of his Pro charger 408 build. He's nice enough to let me borrow it just to eliminate it. BUT so now the general conscious is its the steering wheel position sensor I've been putting on changing? Hoping the get the TB swapped, try that, if no luck then I'm hoping i can also get this steering wheel position sensor swapped today/tomorrow.

Thanks for the help guys, I tend to second guess everything and like to have someone else verify i am on the right path .

BigGun

I can not find anything in my manual that suggests that a bad swps will put your car in reduced power mode. The TP sensors will. That 90 will not fit a stock manifold.

RogerZ06

Your car is 99 ? I so assume your manual is too.

On 2001 if you let the sensor get bad enough. It will cause reduced engine power make dash not work and car not start. I don't even know why I'm wasting my time retyping this.

Logikal1

I had a similar problem. It was saying reduced engine power and would turn over but not start. I was able to get it started by:
Removing fuses 16 and 23,
Disconnecting the battery cables then holding the terminals together for 10-15 seconds,
Then reconnecting the battery cables,
Putting the fuses back in,
Then it started
However now my problem is it had a rough idle and died. Now I'm back to square one and it says "reduced engine power" again and will not start unless the steps above are repeated. Also, once i get it running the traction control light is on and its saying service traction control. The throttle body wires/harness are good and tight and the TB is moving freely. Anyone know where to go from here???

Dnealy

^ to the above posters, thanks but A) the 90mm is not a stock manifold, it is on a fast. The SWPS sensor did fix it. The car was up and running good after replacing it, but NOW i have another situation GRRRRR electrical gremlins.

BigGun

Hmm....I see from your other post the SWPS did not fix your problem. Oh well you needed it anyway and one less problem to deal with. It sounds like a wiring problem to me.

Dnealy

lol It did fix that Problem I drove the car around for a while with no issues, I've put off fixing stuff for so long with all the crap I've had going on and now its all time to fail. If it didn't fix my problem would you suggest I replace it again, or considering it did fix THAT issue would you like to post something helpful or noting at all.

Bill Curlee

SWPS issue WILL NOT cause your reduced engine power. Reduced engine power has all to do with the components of the throttle by wire system which included;

The TAC module, Throttle Position Sensor, Accelerator Peddel Position Sensor, throttle motor and all the inter connecting wiring..

If you turn the ignition ON (engine OFF) can you depress the accelerator and see the throttle blade move smoothly thru it complete range?

BC