Reduced power & Traction control
Thread Starter
5th Gear
Joined: Oct 2011
Posts: 5
Likes: 0
From: Port St Lucie FL
Reduced power & Traction control p1120 p1220 p1221
Hello to everyone here, this is my first post but I have been reading the forum for a few weeks. I purchased my first Corvette a few weeks ago and for the most part it has been problem free.
Coming home from work a few days ago it went into reduced engine power/traction control a few doors down from my home.
Codes are:
p1120
p1220
p1221
c1255
c1278
I checked the TPS sensor and all seems to be ok there. All connections on the TPS, TAC and speed sensors seem to be fine. The day before this happened I recharged the a.c to find there is a leak on the compressor shaft - not sure if these can be related.
Also when I first purchased the car, the rear light harness was hitting the exhaust just inside the pass. rear tire. I fixed those connections and the rear lights and ride control started working, and still are.
Any help would be great, thanks in advance.
Coming home from work a few days ago it went into reduced engine power/traction control a few doors down from my home.
Codes are:
p1120
p1220
p1221
c1255
c1278
I checked the TPS sensor and all seems to be ok there. All connections on the TPS, TAC and speed sensors seem to be fine. The day before this happened I recharged the a.c to find there is a leak on the compressor shaft - not sure if these can be related.
Also when I first purchased the car, the rear light harness was hitting the exhaust just inside the pass. rear tire. I fixed those connections and the rear lights and ride control started working, and still are.
Any help would be great, thanks in advance.
Last edited by Cabbott921; Oct 3, 2011 at 05:59 PM.
Thread Starter
5th Gear
Joined: Oct 2011
Posts: 5
Likes: 0
From: Port St Lucie FL
One more note when checking the TPS sensor the readings were a little different.
Pins 1-3 - went from 0-3.65
Pins 4-6 - went from 3.35-0
Does anyone know what voltages I should get from the pins on the car harness??
Pins 1-3 - went from 0-3.65
Pins 4-6 - went from 3.35-0
Does anyone know what voltages I should get from the pins on the car harness??
Drifting
Joined: Feb 2008
Posts: 1,596
Likes: 67
From: Bahama North Carolina
Thread Starter
5th Gear
Joined: Oct 2011
Posts: 5
Likes: 0
From: Port St Lucie FL
Its a 1997 - nothing has been wet that I know of. only drive it on nice days. just removed the inspection panel to check the PCM and everything seemed fine there as well.
I have reset the codes but p1120 comes back right away. In the key on position REP comes up before the car is even started, then the other codes return.
What voltage readings should I be getting through the TPS pigtail on the car. Pin 1-3 read 0.29 volts pin 4-6 read 4.96.
Thank you.
I have reset the codes but p1120 comes back right away. In the key on position REP comes up before the car is even started, then the other codes return.
What voltage readings should I be getting through the TPS pigtail on the car. Pin 1-3 read 0.29 volts pin 4-6 read 4.96.
Thank you.
Last edited by Cabbott921; Oct 3, 2011 at 06:07 PM.
Drifting
Joined: Feb 2008
Posts: 1,596
Likes: 67
From: Bahama North Carolina
Its a 1997 - nothing has been wet that I know of. only drive it on nice days. just removed the inspection panel to check the PCM and everything seemed fine there as well.
I have reset the codes but p1120 comes back right away. In the key on position REP comes up before the car is even started, then the other codes return.
What voltage readings should I be getting through the TPS pigtail on the car. Pin 1-3 read 0.29 volts pin 4-6 read 4.96.
Thank you.
I have reset the codes but p1120 comes back right away. In the key on position REP comes up before the car is even started, then the other codes return.
What voltage readings should I be getting through the TPS pigtail on the car. Pin 1-3 read 0.29 volts pin 4-6 read 4.96.
Thank you.
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Tech Contributor
Joined: Oct 1999
Posts: 41,058
Likes: 9,820
From: Charlotte, NC (formerly Endicott, NY)
As you know the P Codes indicate an issue in the throttle control circuits. When this happens the PCM sends a message to the EBTCM telling it that it can't perform its part of the Traction Control function and thus TC is inhibited and code C1278 is set. This code will go away once you solve out the TPS/TAC issues. C1255 is another issue. That indicates an internal failure inside the EBTCM logic. Your only hope of solving that issue is finding and correcting an EBTCM ground, connector or voltage supply issue.
If you can get the diagnostic procedures for the P codes you can work your way through them and see where the other problems are located. The procedures are long so are hard to post on the forum. If you want them send me a PM with your email address and I can send you a word documents containing the procedures for each code.
Bill
If you can get the diagnostic procedures for the P codes you can work your way through them and see where the other problems are located. The procedures are long so are hard to post on the forum. If you want them send me a PM with your email address and I can send you a word documents containing the procedures for each code.
Bill
