Bill Curlee asked me to post my experience troubleshooting my defective ignition switch.

I'm an electrical engineer so I troubleshoot electrical things for a living. I thought it might be useful if I showed you my thought process as I troubleshoot this particular problem.

Hopefully this will be helpful for those of you with similar problems.

SYMPTOMS:

The problem gradually got worse so these symptoms are in chronological order:

- Engine would be hard to start sometimes.

- Engine would randomly stop. If you pull over to the side of the road and re-start the engine it started just fine.

- Voltmeter on the instrument cluster would randomly drop in voltage.

- Engine eventually would not start. Voltmeter on instrument cluster was very low in voltage. Instrument cluster lights and a few other interior lights were dim. Yet, other lights in the car were fine. Many messages displayed on DIC (Service AH, TC, etc...).

TROUBLESHOOTING:

When I started troubleshooting the problem, the car was at the point were it would not start. My understanding of the Instrument Panel Cluster (IPC) voltmeter was that it indicated battery voltage with the engine off. I checked battery voltage with the ignition ON (without the engine running) and it was fine. The voltmeter on the IPC however was low, erratic, or zero. Therefore, I determined that if I find where the connection between the battery and the IPC voltmeter is intermittent, I'll will have found the source of the problem.

I started by looking for the IPC voltmeter on the schematic for the car. I figured I would need to then trace it back to the point in the circuit where the voltage is on all the time.






The images above are the schematic of the electrical system from the B+ Bus which is on all the time to the IPC voltmeter. The path to the IPC voltmeter is shown in red. I verified that the voltage at Fuse 47 was indeed on all the time and was at the correct voltage. Moving forward along the circuit towards the IPC voltmeter, the next point I checked was Fuse 15. The voltage there was low and erratic. Notice that one section of the ignition switch resides between Fuse 47 and Fuse 15. Therefore, that switch section or its associated wiring was defective.

The big question in my mind was: why did the engine randomly stop running? A further check of the circuit showed that it also energized the IGN Relay 42 (shown in blue on the schematic). The contacts of Relay 42 goes to such things as the ignition coils. Thus, my question was answered.

To verify my diagnosis, I took a jumper wire and shorted Fuse 47 to Fuse 15 (YES THIS IS DANGEROUS) and attempted to start the car. The car started normally and all the electrical gremlins disappeared.

IGNITION SWITCH

The last remaining question is: Is it the ignition switch or the wiring to the switch?

I removed the ignition switch and shorted across the suspected switch section. I then tried starting the car and it worked like a charm. A phone call to one of my local Chevy dealers and I'm off to by a new ignition switch.

CONCLUSION

Troubleshooting the ignition switch can be summarized as follows:

- Take notes of the symptoms: what works and what doesn't

- Rule out a bad battery: check the battery voltage.

- Using a schematic, locate points in the circuit (fuses, etc...) where you can verify voltage.

- The switch has near zero ohms of resistance, meaning that if there is voltage on one side of the switch and NOT the same voltage on the other and the switch should be closed, then the switch (or associated wiring) is bad.

- About the "associated wiring": remove the switch and jumper across the section to determine if the switch is truly defective (do this only if you are comfortable around electricity and FULLY understand the schematic of the ignition switch).

BE CAREFUL

Some of the fuses in the car are 40 amps. Putting a wire somewire that it doesn't belong can hurt you bad.

I hope this is helpful - there appears to be quite a few of you out there with possible ignition switch problems.

C5_Pewter_Vette

 

All I had to do was look at the marked up schematics and I saw EXACTLY what was going on!!! WOW!!!!!!!!!! Excellent work!!!!!!

You da man!!!!!!!!!!!!!!

That is the very best write up that I have seen in a LONG TIME!

Bill

 

Well, I seem to be having the usual issues (as posted by so many others). For no reason, my turn signals will stop working, half of my stoplights will go out, then the other side, the SVS/TCS issues, a/c cutting off, voltage dropping on/off nonstop....so I think I may have the combination of the "bad grounding/ignition switch issues".....I am losing my mind though at this point in time, its driving me insane.

 

When I was troubleshooting the ignition switch problem, I was overwelmed by all the different things in the car that were malfunctioning. So, I picked a very simple symptom to look at thinking that if I solve that, the other more complex problems might fix themselves (which they did). In otherwords, all the symptoms are probably caused by the same problem. Troubleshooting why a light or voltmeter is not working correctly is easier than troubleshooting a computer that is throwing codes left and right.

Therefore, pick one of your easy symptoms and let's trace it down. Do you have a voltmeter? The missing brake lights or turn signals sounds like the easiest things to troubleshoot. When you say "half your stoplights will go out", what exactly is the car doing or not doing? Do you mean the left or right side lights are out? What about the center brake light? Do they flicker or are they completely out? I can look at the schematic and post them in my replies along with things to look for but I need more specific information on the problem(s).

C5_Pewter_Vette

 

Are there any codes associated with a failing Ignition Switch to help diagnose the problems?

Also are there any codes associated with a Steering Column Lock problem?

I've just started troubleshooting and find it difficult to differentiate my symptoms between a possible bad ignition switch or column lock issues.

As it stands, the car is unpredictable regarding whether it will start or not.

I've also notice recent engine issues: high idle at cold start over 2,000 rpms and low idle once the engine is warm: 600-650 rpm.

I think I'm in BIG trouble...

 

Looking at my notes, my particular ignition switch problem generated the following codes:

PCM:
P1431
P1433

IPC:
B0516

LDCM:
B2282
B2284
U1064

RDCM:
B2283
B2285
U1064

HOWEVER - these codes were being generated by a system that wasn't receiving adequate voltage due to the ignition switch section being bad. Therefore, the code information was kind of bogus. This is why I ignored the codes and picked a low-tech symptom (voltmeter on dash erratic/low) to troubleshoot. The voltmeter is basically connected between ground and the part of the electrical system that is energized all the time - about as simple as it gets. Of course, the connection goes through switches, fuses, connectors, etc... on the way to the voltmeter. I figured if I could find out what was causing the voltmeter reading to be off, then the other issues would also be solved.

C5_Pewter_Vette

 

Also, my switch problem got worse as time when on. The first symptom was hard starting after the car sat for a few days along with a "Charging System Fault" message on the DIC.

C5_Pewter_Vette

 

I just wanted to share my ignition switch experience. It sounds like the switch can cause some strange problems.
On my 97 I would start the car (it started fine) and see that the HVAC unit did not power on…it was just blank. But after a couple minutes it would start working. Also while the HVAC was blank I also didn’t have any reverse lights. These things would work one minute then not the next.
Well thanks to this forum I posted the problems I was having and someone was having the same exact problems. This person’s car was under warrantee so he took it in to get fixed and the dealer found the ignition switch to be the problem. So I decided to try that on my car…after all the switch is not that expensive. After I put the new switch in everything worked great and I never had the problem again.

 

How much does an ignition switch for a C5 cost?

and is there a link on any Forum to Remove & Replace the switch?

 

Take a look at this thread. It has link to two other threads that helped me.
http://forums.corvetteforum.com/show....php?t=1181502
I wasn't able to find any directions for changing the switch but once you get in there it's really self explanatory. You do need to take the console panel off. There are directions for that all over the forum.

 

I’m not yet having major difficulty, but my 2005 C6 is showing one of the same symptoms as your C5 did. The car will shut off at random intervals (not stutter, just turn off as if you hit the switch). It’s happened four times, only once while actually moving. I replaced the ignition switch before any of these problems occurred more due to cosmetic reasons, but I had at least 1500 miles of trouble free driving before this issue arose. The car is otherwise mechanically stock, has 71k on it, and is a M6 coupe.

Any thoughts?

Thanks in advance.

 

The C6 ignition switch is 100% different than the C5 ignition switch in that there are only four small micro switches in it and they are only used to change the ignition mode. The switch also contains a small circuit board. Not saying that the switch cant go bad (they usually CRACK on the face and has nothing to do with them failing) but in my C6 experience, this fault is normally associated with the Body Control Module failure. There are NO actual switches in the C6 switch like the C5 switch that can burn/arc and get dirty.

If the symptoms come back, let me know and I will help you troubleshoot the issue. The OTHER C6 Body control module failure symptom that most people see is when you push the ignition switch to start the engine and the IPC display goes completely BLANK except the little LOCK symbol and the engine will not crank. Some people have found (like me) that if you disconnect the battery for 1 min, and then reconnect it the engine will crank and run. I also found that if you repeatily turn the ignition switch to ON.OFF,ACC, ON OFF, etc,, sometimes it will crank. TRUST ME, If it, cranks, GET THE CAR TO A DEALERSHIP TO HAVE THE BODY MODULE CHANGED!

The early C6s had so many Body Module Failures that the Body Modules were on a couple week to a month back order. As far as I know, unless you have a MODUS or TECH2 with the CAN D module, you cant change the body module. If someone knows otherwise, please let me know. My 06 Z51 Coupe module started having those symptoms but cleared up. I sold it to someone locally and a month after he had it the module failed. We got it running and he drove it straight to the dealership. My 11 Grand Sport has been perfect (KNOCK ON WOOD)

I Got so deep into this failure that I have ALL the 05 Schematics for the Start / Run circuits. Trust Me,, ITS A VERY COMPLICATED CIRCUIT loaded with logic and security with many associated systems. I also found out that the C6 has its very own type of THEFT DETERRENT RELAY type of circuit and that has its own unique troubleshooting and failure modes.

I know this is a C5 section but, you said C6 and I had to go there.. LOL!! Its one area on C6 that I am very familiar with.