2004BlackCoupe

Hi all, I've spent a lot of time reading on these forums and they have helped solve many issues, but I'm out of ideas for the current one and hope that some of you may have some valuable insight.

The story:

2004 coupe had a clutch at end of life and was slipping. Had it parked outside and just before my intended departure for the shop to have the clutch replaced, a rat got into it and chewed several wires. The car wouldn't start (lines had been chewed to the fuel pump as well as several over the clutch housing). Even without a working fuel pump, the engine would give a slight stumble at times so I believe there was spark. The Meziere electric water pump (which appears to be wired to the ignition through a relay) would still run as usual whenever the key was in ON.

The shop replaced the clutch and found and repaired wires for the fuel pump as well as the bundle above the clutch housing that had led to various error codes. Upon first attempting to start the car after repairs, they (somehow) broke the key in two at around the plastic centerpiece. I only had that one key so I was forced to order a new one (they covered the cost).

Now that the new key is here, the car cranks fine but never fires. The water pump also mysteriously does not run with the key in ON, as the line going to it is now always cold. The car has fuel as verified by gauge and you get the smell of fuel from the exhaust after some cranking. The fuel pump audibly pressurizes when the key is turned to ON as normal. The car is throwing no error codes. Disconnecting and reconnecting the battery can lead to the usuals like RDCM or HVAC errors but nothing related to why it won't start; and these errors always clear.

So, is it possible that the new key could cause this problem, or that the box itself is damaged? What process should I use to narrow down the problem assuming there is a hidden chewed wire? Could the crank position sensor have come loose without sending an error code? I have attempted to verify it's connected but I'm not entirely certain which wire it is. I'm leaning towards the one above the starter that is wrapped together with the oil pan sensor line. I can't see where it goes to but the line is taut so it appears to be plugged in properly.

Thank you for reading and for any assistance; I apologize for the length!

Bill Curlee

DTCs


Read and post all the Diagnostic Trouble Codes DTCs that are being displayed!!!

Is the SECURITY LIGHT in the IPC flashing when you have the ignition switch ON??

READING YOUR Engine Diagnostic Codes (DTCs)
The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open etc…)
3) Press and hold OPTIONS
4) While holding OPTIONS, press FUEL four times within a 10-second period.

Initially, on-board diagnostics go into an Automatic Mode which shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each. ( i.e. PCM = 4 codes)
If none are present in a given module, you will see No More Codes on the display.
There are two kinds of diagnostic codes, Current and History designated with a letter suffix, C or ;H. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes.
More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.
Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present;
press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET
To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5.

Here is very good site of DTC definitions:


http://www.gearchatter.com


Make sure to include the H or C suffix!!

2004BlackCoupe

Thanks for the response, Bill. The car is not making any DTCs. I had reset the spurious hvac/rdcm codes and there is now nothing. I can scroll from PCM to RFA with "no codes" always displayed. I cycled the key in and out and attempted to crank multiple times and no codes are thrown.

The security light is not flashing with the key in on. It only flashes with the key in OFF or out of the car entirely and the door open.

Bill Curlee

Have some one attempt to start the engine and HOLD the key in the CRANK position while you at the same time, use a long wooden stick or rod and give the starter a good THUMP See if that causes the engine to crank.

Get back to me on results.

BC

2004BlackCoupe

Looks like the starter is working fine. I progressed through the service manual's "Ignition Relay Diagnosis" section and unfortunately it brings me to "Replace the underhood electrical center". I don't have voltage at the important fuses that it has you check early on:
ENG IGN 1 fuse
INJR 1 fuse
INJR 2 fuse
THROT CONT fuse
A/C Relay fuse

If anyone has any experience with this I would appreciate your input!

Bill Curlee

Check your IGNITION SWITCH! It could be causing the issue..


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

2004BlackCoupe

I've pulled the switch and all of the initial contact readings seem to be fine. Just to be absolutely clear, your diagram indicates that in the ON position, there should be 0-5 ohms between points:

H-B
E-B
F-A
D-A

right?

All of these check out good, as do the 1, 2, and 5 points in CRANK. Is there any reason to continue focusing on the ignition switch?

All fuses in both boxes appear good by checking resistance. Where would you go from here? Remember I have no voltage at the following fuses in the ON position:

ENG IGN 1 fuse
INJR 1 fuse
INJR 2 fuse
THROT CONT fuse
A/C Relay fuse

What components are in line between the ignition switch and these fuses? I'm not getting much out of the schematics.

warlock007

have you verified the wires we're correctly reattached when they found the eaten wires?

Did you check the grounds?

Is it posible that the rats got higher up in the wiring harness?

Bill C is the best at this stuff.

The ignition area, your looking for any burn marks and a solid connection when contact is made.

Was the key properly programed with the correct VAT?

Bill Curlee

Your resistance readings should be LESS THAN 1 OHM. Closer to zero the better. If your are reading 5 ohms, thats an issue.

Retake the readings and see what you get.


I went back and reread the first part of my procedure and YEP. I initatly stated 0-5 ohms but, thats too high. You should not read that much resistance. I fixed the error. Now it says 0-1 Ohms.

Sorry for the confusion.

Bill

Bill Curlee

If your ignition switch is really outputting voltage and you are not seeing voltage on those fuses, you either have a wiring issue between the switch and the fuse box or your switch is failing under real load conditions.

You can unplug the ignition switch and read continuity between the said fuses and the female pins in the connector.

BC

2004BlackCoupe

I've verified what I can see. Given that all error codes have cleared I believe they have been replaced correctly. I don't have proper schematics to check all grounds; I've only checked the obvious underhood ones that I can see.

I feel like for this problem to still be rat related, he would have had to still be in the car when it was initially towed and only at that point found some hidden ignition wiring to chew. Given that the water pump is wired to the ignition relay and clearly ran with the switch in ON before the car was towed to the shop, but now doesn't, it's much more likely to be a mechanic-induced problem.

By the key being programmed, are you just referring to the proper resistor being put in? It does have the same 4.75k resistance as the previous key. This resistance also shows up on the output wire connected to the lock cylinder.

All of my readings are <1ohm. I don't have the schematics to test continuity at this point, I just can't find inclusive electrical diagrams for the system.

Bill, could you explain the significance of pins G, I, and J in your diagram? They never seem to be referenced.

bmackenn

Since you changed keys, you may have to reprogram the key into the car. I had a similar problem and this was the cause. The procedure was time consuming to prevent theft. I hooked up a battery charger, turn key on (don't start) wait approximately 30 minutes (security light goes off) turn key off. Repeat 2 more times turning key on and waiting for the security light to go off. After the third time, wait 30 minutes more then start car. Don't know if this will fix your problem, but it worked for me.

Bill Curlee

Thats the procedure for syncing the security password between the PCM and BCM. As far as I know, it will not allow you to change the VATS resistance value in the BCM set from the factory.

You will have to MATCH the OEM resistor value that you old key had.

Bill

2004BlackCoupe

The plot thickens...

I mentioned earlier that the water pump was wired into the ignition. More specifically it has it's own hanging relay on the side of the fuse box with 4 wires - black and blue going to the pump, a red hot line directly from the battery, and a yellow activation line. The actual underhood ignition relay, #42, is absent.

I had initially assumed that the water pump relay had taken the place of the normal #42 IGN relay upon noticing that #42 was absent. But upon talking to Meziere and actually examining the lines, I realized this isn't feasible; the Meziere relay couldn't be routing power to anything but the water pump.

Upon plugging in a donor IGN relay from an 01 corvette, the car fires up and idles. It sounds rough though and I haven't raised the RPM above idle or shifted into gear. It throws the PCM code P0463, and the HVAC codes B0338 and B2279.

It really appears as though the mechanics that worked on this car stole the ignition relay. If anyone has any knowledge of an arrangement where that relay (#42) was removed for some reason I would like to hear from you. The car does have an MSD window switch for nitrous but it is normally off and hasn't been used in awhile.

I suppose it could be running rough do to a PCM reset I did or the numerous battery cycles. At least I'm making progress.

martysauto

If you only had one key and it and the resistor pellet were broken off in the lock cylinder, how did you order a new key? Even if you get it from a Chevy dealer, you should have had to provide them with an original key to read. There are 15 different resistors. If you have the wrong one, the PCM will not deliver fuel to the engine. No injector pulse.