Quote:
Originally Posted by leo12
Hey bill,great write up on the c5 notorious electrical problems, Need a bit help here,just last summer I noticed that every time I turn the traction control off my c5 the car at times will go into limp mode, REDUCE ENGIE POWER....TRACTION CONTROL FAILURE,in the beginning it wasn't too bad, I would just shut it off wait a couple seconds and off I go,late in the summer it progressively got so bad that every time I turned the traction control of it would go into limp mode and stay there to the point that I couldn't start it back up a gain for a hour or soo,now I'm at the point that I can't take the traction control off and that's no fun.anything more I should be looking at said the grounds?.
Lets start with a good fresh DTC read using the IPC DIC.

Erase/clear "ALL" the old DTCs. Then take the car for a drive and make it fail.

When it fails, press RESET/ CLEAR to get rid of all the messages/warnings. When there all gone, read and post ALL the DTCs "BEFORE" you turn the ignition off.

Make sure that you include all the prefixis and H/Cs

With that data, we can get to troubleshooting.


Bill

Hey Guys
Its ben a little while sense i was able to get back on the Vette,so heres the story after i got the car ready for the summer,A couple weeks ago i drove it a few times with no problems.
Two days ago i started the car and the car engine lite went on and flashing reduce engine speed,the traction control went off,by it self and service traction control was flashing and it went into limp mode.i pulled the codes and here they are.All the engine grounds and traction control ground have ben addressed and are in proper working order.
I would like to hear any recommendation,fixes that will allow me to enjoy this Damnnn Vette again .
Thanks for all the help.
P0102 = Mass air flow sensor,H(Note )There no Mass in the car,Speed density tuned.
P1220 =TP sensor 2. H-C
P1221=TPsensor ,1,2 performance H-C.
U1016=Loss of comm with PCM , H
U1064 = Loss of comm with BCM both H.
U1096 = Loss of comm with IPC , H
C1278 =TCS temporary inhibited by BCM, H-C (Note) when i reset this code that is when the engine lite and reduce engine speed goes off
C1281= Steering sensor,H (Note) the steering lock has be disabled/bypassed for 7 years now

 

C1281 is the steering position sensor not related to the column lock mechanism. The steering sensor could be the cause of all of your problems.
What year is your car?

 

Hey Mr. Leo !!
Below is info as relates to a 2001 Corvette:
The DTC's 1220 and 1221 are causing your "reduce engine power" when either of those two DTC's set. Would have to do some digging into why the Traction Control message illuminated also.
The P1220 will set if the TP2 signal is less than .13 volts or greater than 4.87 volts for less than 1 second. P1221 will set if the TP2 disagrees with TP1 (there are 2 TP sensors within the TPS housing) by more than 7.5 %.TP1 is a "pull up" circuit and if you connect your DVOM to the dark blue wire the voltage should be less than 1 volt at idle and above 3.5 volts at WOT. TP2 is a "pull down" circuit and when you connect your DVOM to the pink wire you will be reading about 3.8 volts at idle and below 1 volt at WOT. These were the voltages readings from my 2001 back probing wires with KOEO.
White and Purple- Low Ref. - .03 volts (should be less than .1 Volts)
Yellow/Black and Green- 5 Volt Ref.- 5.01
Dark Blue- TP1 Signal - 1.09 Volts idle- 4.32 Volts WOT
Pink- TP2 Signal -3.94 Volts idle- .71 Volts WOT

Enclosed is pictures of the TPS Sensor 1 and 2 signal voltage at idle and WOT

 

The car is a 1998,is there a way to test the sensor?

 

777,i will check the sensor and see what it reads, or should i just change the sensor?

 

Well what if it were a wiring problem ??...you can change 100 sensors and it still would not work...right ??....it's always not a bad part !!...the test only takes 15 minutes but you will KNOW that the wiring integrity is OK.
I'm sure you have a multimeter so the first thing is get some t-pins like the ones I'm using in the pictures. I got mine in a box of 50 from Amazon years ago but you can probably find them maybe in Staples or a Michael's...or if you have a thin thin paperclip and unbend it that will work. Just go straight in with the clip until you feel it hit the back of the pin....With key ON and engine OFF you should have:
1) white and purple are low ref. grounds-- should be less than .1 volt
2) yellow/black -- 5 volts ref. and the dark green -- 5 volt ref.
3) dark blue-TPS 1 signal-- less than 1 volt at idle and above 3.5 volts at WOT (pedal to the metal)
4) pink wire TPS 2 signal) -- about 3.8 volts at idle and below 1 volt at WOT (pedal to the metal)
Let me know if you have any issues. I did a video with my Labscope doing a "TPS Sweep" a few days ago and will post it here...not the best video, I was using my iPhone....and this is the BEST way to see what the Sensor is doing...a voltmeter can't pick up any drop outs that would affect the TPS's operation !!

 

This is going to sound strange, but try this first...

Next time you start/ drive the car and you get the service traction control/ reduced engine speed error...open and close your passenger side door repeatedly. The wiring harness in the passenger door gets frayed at the joint where the loom enters th door panel. Inspect this area/loom for exposed wires. It's tight but accessible without removing door panel.

This happened to me many years ago while driving on the highway. I researched solutions and causes on the forum and Google, and that was the cause of my issue.

I located the frayed wire in the loom and taped it off with thick electrical tape. Issue resolved and problem never reoccured after 10+ years.

Good luck!

 

Post script...there is a plastic loom over the wiring harness between the body and the door. This loom is relatively easy to pop off to access the wires between the body and the door.

 

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