This morning I went to move my 01 Z06 to my new parking spot, and the battery is dead. I got the car recently from a dealer and I figured it was just on its last legs.

I get a replacement from Autozone and it powers the electrics. I go to start, and the battery turns the engine over but I don't get a startup.

First symptom:
The display reports LOW FUEL and the gauge shows empty. When I parked it, it was about half full.

Other symptoms:
- The radio doesn't come on. I've read that this is a PCM/BCM issue?
- The key fob doesn't lock/unlock or pop the trunk
- Connecting my scanner to the ODB-II port does nothing. It sticks at Connecting...
- A small puddle of water on the driver's side floor. What the heck? I'm guessing some of the drains are clogged?
- When I walked away from diagnosing the car, I noticed the trunk lid had opened on its own. I checked the fob again and it still didn't work. I don't recall bumping it on the dash, but it's possible.

I've got to tow the car today, either to my new parking spot or to a dealer if it's expensive PCM/BCM replacement time. According to this link:
http://www.digitalcorvettes.com/foru...ad.php?t=79039
A shop needs to have the car set a new PCM to the car.

I don't really have the ramps to work on the car, and I'm pretty busy with work right now. I hate to have it towed to a random dealer, but I think that's the most straightforward move for me.

Does this sound like a pretty clear case of PCM failure? The car was running fine the several times I'd driven it before the battery died.

Is modifying the rubber drains to stop clogging something that is hard to do with the car on the ground? If so, I'll try to tell the shop to do it.

The tow truck hasn't arrived yet, so if there's obvious things for me to do on my own before sending it to a shop, I can have it towed to my new parking spot.

Thanks!

 

If the truck is already on it's way you probably won't have time to check much... The fact that your obdII scanner won't connect probably means no comms with the pcm. Try to pull your codes from the DIC in the car (you do not need an external scanner to pull codes on the C5) See below for instructions... My guess is you'll just see a bunch of no comm messages but it's worth checking (courtesy of Bill Curlee)

If you have time to check the wiring harness going to the pcm located inside the fender just back from the passenger side wheel well (pretty much right underneath the battery) you should make sure it's plugged in tight. Sometimes battery acid that has leaked onto the PCM or the wiring will cause this kind of failure so look for that too...

Also, I know it sounds stupid, but make sure your battery terminal connections are tight (If you have a torque wrench the proper spec is 11 ft/lbs).

Good luck

 

Call me asap! Pm sent!!!!

 

Arg, I wish I had checked back here sooner. Just got bak from rolling it onto the flatbed.

I didn't have time to pop the wheel off and look inside the access panel. The car looks to have been really clean before I got it, but who knows would have been under there.

I checked the new battery before I hooked it up and it was at a healthy 12.5. It really didn't sound like it was struggling to crank. I didn't wrench the battery terminals down super tight, but I thought I'd made a reasonably solid connetion for each post.

The passenger floor was not visibly wet and didn't feel moist at all to the touch.

edit: I did have the presence of mind to take pictures of the bodywork before the truck left, just in case the shop or the tow does any extra damage. Hopefully not an issue.

 

DO NOT CRANK DOWN ON THE BATTERY TERMINAL BOLTS! They need to be tightened down to 11 ft/lbs for 97-2003 C5s and an inch pound value for late 03-04 C5s. (CAN NEVER REMEMBER THE VALUE!)

Too tight and WHAP,, you will need a new battery!

 

I didn't. I would say I did it nice and hand tight, but not anything extreme.

Bill, I will try to call you this afternoon. At the doctor's right now.

 

bad ignition switch

Bill and I have both 'been there, done did that'

 

My car started out with the same problems you are having with the car not starting and the radio not turning on. After about half an hour trying to troubleshoot, I disconnected the BCM and reconnected it and the car started right up.
This fixed the problem for a few days. Now my car sits in the garage because it shuts off after driving faster than 2mph.
Good luck on getting yours back on the road.

 

Found this very new post about testing the starter solenoid:

I can tell the dealer to check the solenoid (who hasn't thought to whack a starter?) but don't the facts that my starter cranks and my radio won't turn on point to something else?

 

In your case ABSOLUTELY NOT! You either have a serial data buss issue cause by moisture on the BCM or You have an issue with the door connectors.. That why I wanted you to call me. Its easier to tell you what to do than peck out all the stuff on the computer.

OPEN BOTH DOORS. Shake the hell out of the rubber accordion tubes between both doors and see if it will start.

See if theres ANY moisture on or around the BCM in the passengers foot well (big silver box) Feel under the carpet and see if it is wet.

Report back

BC

 

 

Somehow I may have accidently pointed him in that direction (answering too many post at one time!)

Anyway,,, Prove out the simple stuff first and that will help us point you in the correct direction.

READ and POST your DTCs again.

READING YOUR Engine Diagnostic Trouble Codes (DTC)

This procedure should be carried out any time you experience a problem with your C5. Most inexpensive store bought aftermarket code readers will ONLY read power train DTC’s. Reading the DTC’s with the C5 built in code reader will allow you to read ALL the modules in the vehicle.

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 ect)
3) Press and hold the OPTIONS button
4) While holding OPTIONS, press FUEL button four times within a 10 -second period.

Initially, the on-board diagnostics go into an Automatic Mode which will cycle through each module and 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 module. ( 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 types 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. There are a few body module DTC’s that if set will prevent the module from operating properly. Once the DTC is cleared, the module will return to full function. This is not true for power train DTCs.

If you have never read and cleared your codes, there will probably be a lot of old history DTCs. It is recommended that you clear your codes and see if any come back during a driving cycle. Those are the ones that you need to concentrate on diagnosing.

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.

NOTE and a WARNING. You can read the DTCs while the engine is running. I pull mine up all the time while driving.
WARNING. Don’t become distracted while reading DTCs while your driving and cause an accident!!!!! Use common sense and drive safe.

These are some very good C5 Diagnostic Trouble Code (DTC) explanation web sites!!! They also explain how to read the DTCs

Here are some very good sites that explain what DTC mean:

http://www.gearchatter.com/viewtopic11755.php

http://www.obd-codes.com/trouble_cod...d-ii-codes.php

Make sure to include the H or C suffix when you post your DTCs!!

 

The dealer won't give me an update until Tuesday. When the car was at the dealership, the battery was flat, so I couldn't initially read the DTC codes (I was instructed to look at these before buying the car). But I did read them when I picked the car up. I'm printing them below. Now mind you, this was a month ago, and even then, all the codes were H. I know some of these are BCM comm problems, but I figured they had to do with the low battery, not an ongoing issue. Maybe I was just blinded with love.

C1276 H
B0432 H
B0502 H
B0507 H
B2482 H
B2527 H
B2587 H
B2592 H

B2282 H
B2283 H
B2284 H
B2285 H
B2286 H

U1064 H
U1255 H

I'll try to get the dealer to tell me what codes it's posting now. If there's a major PCM / BCM comm issue, will it still register DTC codes?

 

The dealer got back to me. Apparently, the PCM locked out in a theft mode after the car couldn't get started after 10 attempts from the battery replacement? I think I definitely tried that many times, but I don't get why it would have locked me out in the first place, if everything else was normal.
The car started for them on the first try, and all subsequent tries.

No water in the passenger footwell. The water in the driver's footwell was from cracked stripping and scuttle at the base of the driver's windshield, which was leaking water into the cabinNo apparent corrosion or harness issues were found with the BCM.

The new codes picked up were:
P0650 <-- I need to check with them that the MIL lamp is still working on key on. Any other way to confirm it's working? I definitely didn't see any MIL during my initial starting woes.
P1626 <-- cause of the starting condition?
U1301 <-- battery related I assume

 

P0650 indicates there is a failure in the MIL circuit so the lamp will not light. As you say you should find out whether the MIL lights at key on.

P1626 is a little more difficult to figure out. From the SM:
Circuit Description
The body control module (BCM) produces the theft deterrent crank relay and fuel enable signal when ignition is ON and the proper ignition code voltage value is detected. The powertrain control module (PCM) monitors the fuel enable signal during crank. If the proper signal is present on the Class 2 Serial Data Circuit, the PCM enables the fuel delivery in order to allow the engine to start. If the PCM determines that the fuel enable signal is not present or incorrect while the engine is running, DTC P1626 is set. The engine continues to start and run as long as DTC P1626 is stored. If the problem affects inputs to the VTD signal, the starter motor may be disabled.

Conditions for Running the DTC
The engine is running.

Conditions for Setting the DTC
The PCM has detected a loss of the state of health serial data message from the theft deterrent system.

Action Taken When the DTC Sets
• The body control module (BCM) send a class to message to the instrument panel cluster (IPC) to illuminate the SECURITY indicator.

• The powertrain control module (PCM) will not illuminate the malfunction indicator lamp (MIL).

• The PCM will store conditions which were present when the DTC set as failure records data only. This information will not be stored as freeze frame data.


Bill

 

To follow this up -- I've been happily driving the car around for a couple weeks now. Since it's come back no issues have cropped up and the car is in working order. It's rained a few times and no water has built up in the footwell, which is good.

I really hope it was as simple as a triggered theft system causing the car not to start. Though the fact that it cranked doesn't really match the DTC's description of how that was supposed to work.

 

so my 2003 Chevy Corvette AC is having issues every time I click the AC button. It is not turning over the compressor. I’ve checked to see if the compressor is good. It’s good. I’ve checked if there’s free on the high and low pressure sensors are good. All the fuse is all the grounds are good. Can’t figure out why it’s not working tried hooking up a scan tool to it and it had no communication with the HVAC system was wondering if I had a bad PCM unit, but I would take the unit and turn it upside down around to get it on its spot. It would automatically turn the compressor on with just clicking the auto button and everything would work fine but when I try to put it back in the spot that it goes to, it won’t come back on , so we have no other ideas on the problem

 

First there is only 1 pressure sensor...if you have a "no comm" with the HVAC module it's not a bad PCM...is this an auto or manual HVAC ??…if manual you will see a no comm because the HVAC Module is not on the data bus !!…for an auto (RPO CJ2) HVAC no comm you would check that modules (HVAC) power and grounds...what are you turning upside down ??…can you please start a NEW post with your concern ??…there are 3 wires at the PCM if that is what you are turning upside down that you may have issues with.

 

and this is a auto HVAC

 

I have an auto HVAC unit and I fiddled with the four grounds that are located in the front of the car. Don’t know if that has anything to do with helping that. also the HVAC module itself when I turn it a certain way everything starts reading right the AC comes on by itself when clicking the auto button and when I move out of that special spot, everything just shut off, but I just got a new module put in and it doesn’t do that anymore and now when I turn it a certain way to get it back in that spot nothing happens so I don’t know if it’s a wiring or a problem but also the scan is saying that it’s not communicating and it’s a big problem with it. If I can’t figure out what it is, if I can’t communicate.