I had been having some weird rarely occurring electrical problems, but seemed to always be something different. Throwing numerous different codes at different times, TCS and ABS, and finally getting stuck for a little while sometimes when trying to start the car. I had a leak from my coolant reservoir tank out the bottom near the T, which happens to be right above the ground connector that was extremely dirty and somehow the eyelet connector was broke and almost not even under the nut. So thank you, thank you, thank you Bill C. You are the man!! Electrical problems are the absolute most frustrating difficulties to diagnose and this simple check saved me from nearly buying a new switch ignition, or at least fixing it with your guide!

I can not say enough how grateful I am for this wonderful resource us Corvette owners have. I tell my friends if they want to start learning about cars, get a Vette then you have all the knowledge available to you on this amazing site! Thank you so much!

 

Maybe the following will be of some help. Your mileage may vary of course.

My story:

I have an 04 with 2K miles which is rarely driven and never been out in the weather, mostly just stays in the garage connected to a battery tender. One day about four years ago when I took it out for some exercise I got "Service ABS, Service Traction Control and Service Active Handling" messages in the DIC. A check of codes produced the following:

C1282HC Yaw Rate Sensor Bias Circuit Malfunction

C1284HC Lateral Accelerometer Sensor- Self Test Fault

C1285HC Lateral Accelerometer Sensor Circuit Malfunction

C1287HC Steering Sensor Rate Malfunction

C1288HC Steering Wheel Position Sensor

C1296HC Master Cylinder Brake Pressure Sensor Circuit Open Or Shorted

C1233H RF Wheel Speed Circuit Open or Shorted

C1237H High System Supply Voltage


I reset all the codes and most disappeared except for C1233HC and a new one, C1283HC (steering wheel off center) which was weird because this car has not ever been taken apart in any area and certainly the steering shaft has not been touched. Both C1233 and C1283 remained and persisted and because there was no EBCM failure code that I could see (such as the infamous C1214 or C1255) I launched into posting a lot of questions here and checking grounds and connections over the past years, etc. Since I don't need the car for transportation it was not particularily important that it get fixed right away so I just researched it in my spare time and tried things from time to time. At first I was convinced my problem was somewhere in the vicinity of the RF wheel speed sensor so I checked resistances in the wiring and connections and checked for voltage output on the AC millivolt scale and I had that. Finally after four years I called Jason Durr the Corvette specialist at City Chevrolet and he told me I was probably wasting my time trying to figure out the codes and just bring it in and get a new EBCM so I did.

Jason installed a new $1000 EBCM and informed me a few minutes later my car was fixed and he was right, now it is.

Oh well, It was good experience seeing if I could fix it myself. C5's are sure nice to drive when everything is working, I should try to do that more.

Regards, Greg

 

Bill,

Been having some starting problems lately and figured the battery was going (4yr old delco). Took it to the Zone and they said the alternator was not charging the battery. Looked like about 11.x volts from the regulator.

I tested the battery with the ignition off and got less than 11 volts (my meter is really cheap...)

With the ignition on I was getting 13v between the battery and the main red cable to the alternator as well as at least 12 on each of the small red wires in the plug to the alternator (i think those are the fusible links).

Is there any other way to confirm the charging voltage coming from the alternator going to the battery? The Zone guy is telling me it should be way more than 11v.

Could this be a alternator grounding issue from the case?

Here are pics of the tests with engine running:


The Connector



First red wire next to the open/unused pin



Red Wire to the outside of the connector



Main battery cable

 

How are you reading 13 VDC on the back of the alternator? If you read that connection with the engine OFF to chassis ground, what do you get;

Read that connection with the engine running to chassis ground:

Read that connection to the positive battery terminal

Bill

 

Bill,

The black lead is connected to the neg terminal on the battery. I will go and test like you suggested and post.

 

k,

Red lead on the main battery cable on the alternator and the black lead to the chassis ground on the rail right next to it read between 13 and 14v.

Red lead on the main battery cable on the alternator and the black lead to the Positive battery terminal, no voltage but there was continuity. Not sure what kind of resistance value you would expect there.

Is there a reading for the expected voltage charging from the alternator to the battery?

 

I also tested the alternator case/ground to the chassis ground and got 0 ohms and alternator ground to the negative battery terminal and also got 0 ohms.

correction from an earlier post I have no resistance from the alternator connection/battery cable to the positive battery post

Also perfect continuity (with car off) from the small red wire on the end to the positive battery terminal.

So, what I think I know is that the grounds in the charging system seem to be OK (I also cleaned the ground right under the battery), I have more than 12v in the system when it is running, but the battery does not seem to be getting a full recharge after being used.

Still don't know how to tell if the voltage going back to the battery from the alternator is within the expectations.

I might be rambling now...does any of this make sense or am I barking up the wrong tree?

 

If you measure the voltage directly on the battery terminals and it above 13.0 VDC,,, the alternator is outputing. The desired charge voltage is 14.5

What you read on the battery terminals, should MATCH what you read on the BATT terminal on the back of the alternator to ground.

How did you check for continuity? With the battery in circuit or out of circuit?

BC

 

Bill,

I'll check the voltages again at lunch and post.

As far as continuity goes, I wanted to see if the fusible links were ok so I went from:
1. the positive battery terminal on the battery to the battery terminal on the alternator
2. the positive battery terminal on the battery to the small red wire (D) on the 3-wire plug.

I was also checking continuity between the frame ground and the alternator case, case to the neg batt terminal and frame to the neg battery terminal. Seemed to be pretty good, 0 ohms mostly. Hard to tell if the spots I was testing from were clean and bare, It was getting kinda dark...

I did get a code one time last night on the IPC, Low Voltage and the P1638. I cleared the code and started the car, but it did not return.

I have the battery on a tender right now so I can test a bit more at lunch.

 

Bill,

I think this may be an ignition switch issue. I remember a while back having an issue where it wouldnt start but after cycling the ignition it went away.

Had the battery on the tender all night and today it was at 12 v. Showed the same from the battery to the alternator, and alternator to frame ground. When running all voltages we're at 14 plus, like they should be.

I found another thread you posted about checking the resistance of fuses with the key off and on to test that switch. I'll do that tonight and post the results. Hopefully that will be the issue and it'll be a quick easy fix.

If that is the issue, I'll finally get to fix the dim HVAC display while I'm in there.

 

Correction....

Just checked the fuses under the hood and with the ignition in the "On" position, I have batt voltage on all except BCM 13 Fuse#22. I dont have that one.

Under Hood Fuse Center

ENG ING1 FUSE# 19

INJR 2 FUSE# 18

THROTCONT FUSE# 17

INJR 1 FUSE# 22

PCM FUSE# 16

F/PMP FUSE# 13

Instrument Panel Fuse block

BTSI BU Fuse# 21
BCM 13 Fuse# 22
IPC Fuse# 19

 

Hey guys great thread. I have a slight variation on the "dash lights flashing but still drives". I use HP tuners to program my car. Worked fine for a year. The randomly started the flashing warnings. I turned off and back on and it was fine. Now, often when I use the tuner, conneceted to the ODBC port, it times out with errors like "unable to write to XXX, retrying" It tries 20 times then aborts. Tune is lost, car won't start. Fortunately there is a "recovery" process that put the tune back in the last five times it has happened.

The XXX location of the error seems to change with each "crash". Any ideas?

Also I cleaned the 4 underhood grounds - all looked good. I checked the connecitons in the door pillars, looked good but cleaned them with electrical cleaner anyway.

 

Without picking your brain and having you dig for more clues,, Try this:

Rebuild your ignition switch and check your door wiring harness connectors for damaged female pins. Those are the TWO most common C5 issues and could very well be your issue.

- C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html


When you up-load a TUNE,, you MUST make sure that the battery is fully charged AND,,,, you DO NOT change any loads.

 

Sorry Bill but is that for future tech or me?

 

SORRY... I get caught up in the ISSUE and forget who the OP is.. Future tech..

BC

 

Thanks Bill, would it make sense to just replace the ignition switch?

 

Trust your first instinct, not the guy at AutoZone.

Ya know, I thought the battery was going bad but went to the Zone to have it tested. The guy put the machine on and it said that the test could not proceed until the battery was charged but he went on anyway. then it said the alt was bad, should have said something.

Took the battery to another store after having it on the trickle charger all night and it showed 12.8V but only 41% capacity. Bad battery.

Gonna pick one up from wally world today. Probably upgrade to the maxx78. Later this week I'll have the charging system checked again just to be sure the alternator is putting out like it should.

Had the salt tested after installing a new battery, came out fine...

Thanks for the help, I'm glad it wasn't so bad.

 

I am having what seems to be the same trouble with the reduced engin power with a slight twist. Last night on my way home from work, I was crusing at 60 mph when I got the traction control/reduced engine power. I stepped down on the accelerator and nothing, I let up on it and nothing, still staying right at 60. Cruse control was not on. I pushed in the clutch and the engin reved up. I had to kill the engine and restart it, all at 60 mph, to regain control of my cars accelerator. I will clean the grounds, I sure don't want that happening to me at the track or when I happen to have it floored. Anyone else ever experiance this? Thanks for your imput. BTW this is on my 02 Z06 with a TVS 2300, LT headers, and a non catted X pipe.

 

The very first thing you should have done was read the DTCs before you turned off the ignition. The DTCs are the only way any one can make a logical recommendation on whats wrong.

Read and post the DTCs


The things that cause reduced power are not chassis ground related.

Bill

 

would have been hard to get the codes at 60 mph lol. I will get the codes tonight. I cleaned the grounds in the engine compartment and drove the car to work today, so far so good.....