Well it is def. loosing fuel pressure...because when it dies...although I have no fuel pressure guage...not much squirts out of the rail when I press the Schrader. I don't know about spark...but it sure is weird to have the blinker/flasher system linked to the stalling.

 

A big thanks to Bill. This thread saved me who knows how many hours, days, weeks, months of troubleshooting and who knows how many $$ buying new PCM/TAC, etc.

My problem - small ground wire on G106 was broken at joint from wire to connector.

Symptoms - complete PCM failure. No power to PCM. Couldn't read codes on DIC or use scanner. Many failure errors (Reduced Engine Power, etc.) when turning key on.

Background - car was largely disassembled by my "crew" which consists of my brother-in-law and his two sons for a conversion from SCCA T2 class to NASA ST2 class. This included complete engine rebuild and dropping the drive train to add billet aluminum coupler in place of stock GM rear coupler in drive shaft, and a new C6 Z06 clutch which I couldn't use in SCCA T2. Disconnected many ground wires in this process, but we take the engine out every other year or two, so this wasn't new.

Upon first attempt to fire the engine, no power to PCM. I wasn't at my brother-in-law's garage so couldn't help until today. He spent three days looking at all the ground wires, connections, checking electrical continuity, and changing the two PCMs I had, etc. Couldn't find anything. Today I finally had time to help. First found this:
http://forums.corvetteforum.com/c5-t...m-failure.html

Symptoms very similar to mine and I was very worried we had fried two PCMs.

I read many pages from this thread and we went back to ground wires. Checked the pin connections and they were all clean, then found post #1560 on page 78 - went to look at that little ground wire and when we looked it was broken. We had connected it correctly (we mark all ground wires with yellow tape), but in process of connecting it (after many times on and off over the years), it must have just broken. Resoldered a new connector, reconnected the header, exhaust and everything else - PCM had no codes and the new engine fired right up!!! Race season, here we come.

Bill - I owe you one for all the time you put into posting on this thread (and many similar ones).

 

C66 Racing: While soldering wires gives you the best possible connection, I have stopped doing this in race cars years ago. Soldering makes them very brittle. Over time they will eventually break. I only use solderless terminals now with the built-in heat shrink, or the bare terminals and use my own heat shrink. Race cars are pretty brutal on wiring, and it sounds like you remove and install your stuff a lot, just like I do with my stuff. I have found broken wires too that were soldered. It is always those darn grounds!

 

I took the battery out to see what is going on under there...looks fairly clean and innocent for a 14 year old car...I did notice some fraying on the shielding over the big harness...photos enclosed. I am going to test the battery again...what should the voltage be between the terminals? Again car starts and idles well...you can blip the throttle and rev it up fine....if I turn on hazards or turn signals it stalls immediately. If I drive around the block briefly, it stalls as well.

 

Bill,
I have another issue I just noticed today while driving my 2000 c5 convertible. I noticed my oil pressure gauge needle is maxed to 80psi and stays there. On the screen for oil pressure it stays at 130. I pulled over and turned off car waited about a minute and started up and gauge needle went right back up to 80 psi and 130 on screen. Will this damage my car? Is it an electrical bug in the gauge? Please help

 

Hi Again....today I got ambitious and took out the battery...cleaned the grounds under there..cleaned the chassis grounds near the headlights...charged the battery fully. I reinstalled the battery....car started right up . I actually let it idle for half an hour...blipping the throttle from time to time...every was normal. I tried the blinkers and they worked fine this time...car did not stall. I then put it in gear and proceeded to drive in first gear...only got 25 ft before the car died. It would not restart...so I managed to roll it near the curb and parked it. No codes.

I am starting to feel that this problem may be related to the steering wheel recall...although there are none of those codes. I think they simply replaced the lock plate in the steering column and did not put in a K harness or any other electrical gizmo...maybe this is shutting off the car...I think I will order an lmc5...its only 45$ an worth a try. Other than that, I will be checking the grounds near the seatbelts next.

 

echelonphoto



That wiring harness is HOSED and until you untape it, inspect the wires, you wont know if that is the cruxt of your issues.

Bill

PS,,,, You had an acid leak some time in the past!!! I would get that rust take care of ASAP or you will eventually need a new frame or frame repairs.

 

Thanks, Bill,

Already took care of the rust....I will look at the wires more closely...is there any way I can test each wire without actually breaking the insulation? Is there a diagram of the wires in that bundle? I can understand that a bad wire can cause poor running...but how can the car run so long and well when still and then poop out when you start moving?

 

See,,,, MURPHYs Law,, PFM,,, Something is rotten in Demark..... Until you untape that harness and inspect the wires,,, Its a CRAP SHOOT..

Something is COMINGLING that shouldnt be. The ODDS of guessing are tremendous. (Turn the blinkers on and the car dies) WTF????????? See, It doesnt make sense.

So,, GET UN-WRAPPING~

Until you can prove that harness good,,,,,,,,,,,, Your on your own..

BC

 

There is no legend for the color coding of the wires?

 

Can I assume each of these wires has a corresponding fuse? So I can check resistance thru the fusebox....I AM willing to go the distance with this....this car WILL be made healthy!

 

Well there is sort of... You just have to know how GM does business.

RED = B+ Hot at all times
Orange 12 VDC switched
Pink Is switched power to components
Black and black with white stripe are circuit grounds

ALL the other wires are identified by the FACTORY SERVICE MANUAL by color and gage. Sometimes you will find a harness with three of the same color wires. Its tough to figure out which one goes to what unless you do a continuity check or actually follow the wire in the run.

What difference does it make. If the wires are damaged, fix them. You can use liquid electrical tape if the conductors are not damaged If the wire strands are corroded, burnt or broken, find the same gage wire and some heat shrink and solder splice in the repair. Heat shrink cover the repair site.


Remember that I said, way back 16 post ago that you could have had acid damaged wiring. Seen it too many times. Turning the blinkers on should NOT have any thing to do with killing the engine UNLESS some circuits that should NEVER connect are connected.

The ONLY way you are going to resolve this is to completely unwrap that harness and any other one that was exposed to the acid, neutralize the remaining acid, repair the damage and fix the rust on the frame.

Let me guess. I bet Your HVAC system had NO damper control also. The harness has a vacuum line inside it, its probably dissolved and also needs to be replaced. That vacuum line provided vacuum to the damper door vacuum servos under the dash.

Please snap a picture of the harness when you separate and narrow down the damage

Bill

 

Here are some things in the service manual that might help you:

Document ID# 303644
2000 Chevrolet/Geo Corvette


--------------------------------------------------------------------------------

Repairing Damaged Wire Insulation
If the conductive portion of the wire is not damaged, locate the problem and apply tape around the wire. If the damage is more extensive, replace the faulty segment of the wire. Refer to Splicing Copper Wire Using Splice Clips and follow the instruction to repair the wire.

Wire Size Conversion Metric Wire Sizes (mm 2)
AWG Sizes

0.22
24

0.35
22

0.5
20

0.8
18

1.0
16

2.0
14

3.0
12

5.0
10

8.0
8

13.0
6

19.0
4

32.0
2

50.0
1/0



--------------------------------------------------------------------------------
Document ID# 303644
2000 Chevrolet/Geo Corvette

 

Thanks for the tip. We actually used a connection that you apply heat to inside a pre-heat shrinked wrap. Solder had to be in there but we didn't use our own. We'll keep an eye on it - at least now I know what I'm looking for!

 

Thanks Bill,

Going away this week...will tackle this job when I get back and take photos. Not really new to me...I bought a salvage Infinity a few years back which had light damage...but engine was missing considerably...the crash had damaged some of the wires going to the maf...not obvious until I got into the harness, found several torn wires...a little solder and shrink wrap and the car ran great.

The vacumn line seems to be ok...it was not in the harness I believe most of the damage was due to the harness chafing against the bottom of the battery tray...once fixed I will cushion it with some foam wrap.

Just a little background on this car...I bought it two years ago from the original owner at 95k miles..I have enjoyed it as a DD since. We have done quite a bit of work...new suspension, new c6 z clutch, rebuilt torque tube, complete c6z exhaust system, larger maf...all done on the ground with jackstands...so a little electrical work doesn't scare me...I hope it won't take forever to sort out

 

Hi Bill and all contributors,

Well...after days of troubleshooting and trial and error...today I thought...why would the car stall only when moving? Some wire must be moving and either shorting or losing ground...I peaked under the rear left wheel to check the ground at the rear frame behind the axle...guess what?....the nut was totally loose, backed off a 1/4 inch! We must not have tightened it enough when we did the clutch job. Anyhow...I tightened it securely and all seems to be well now....This should be a sticky! Fuel was cut off when the wire lost its ground...I just do not know why starting came back after it sat for a while.
Thanks Bill and all for your help...I will get to sorting out my harness issue and get everything back together...ALWAYS check ALL your grounds first....listen to Bill.

 

Well...just drove around for an hour and car feels great....I forgot how fierce it is when you get on it! In a way I am glad this happened...gave me an opportunity to learn and also discover some things that needed attention ..like the rust and harness below the battery...inspected that thoroughly and all wires are intact...I wrapped it thouroughly with good electrical tape and then wrap some sticky heatshield around it to cushion it from abrasion...I found that the battery tray has protrusions that contact the harness directly...so I made sure to put extra padding there.

Its amazing how one wire can cause so many problems...I am glad I listened to everyone and didn't start throwing parts at it or bring it to a dealer....any need any help...if I can please contact me.

 

Devilred....its the oil sending unit...they do that when the go...part is cheap, but you have to take of the intake manifold to get at it. You will not hurt your car driving it like this.

 

Thanks, after some research I found out that the opsu is very common to crap out on the c5. Happy it ended up being that and not something more serious. Having it replaced tomorrow.
#Vettelife

 

Thanks for the help. I finally think I solved it, The voltage regulator in the alternator was overcharging then undercharging. Replaced it and so far no more problems. It caused all kinds of weird stuff to happen with the lights and gauges. If your voltage gauge is moving around very much check the alternator. Take it off and test it. Testing it on the car didn't detect the problem on mine.