I've got an 02 Z06 with 67K miles on the odo, became the 3rd owner at 50K, promptly had to replace the EBCM (about $700 out-of-pocket) and cleaned all the ground connectors at that interval.

At about 62K, the sterring column locked up for the first time, but I managed to work around the problem by whaking away at the steering wheel. A local Chev dealer ran my VIN, which indicated a factory bypass had been installed by the previous owner and I therefore did not qualify for a no-charge GM "final" solution under the recall.

The only mods to the car are a K&N CAI, a Callaway billet TB and a DiabloSport Predator performance tune

Of course, the column then began locking up every month or so, and I continued to use brute force to get back on the road. In no case did the "reduced engine power" warning come up or did the motor fail to fire up due to the fuel cut-off feature ... until this morning.

This time, with 67K showing on the ODO, when I slipped the key into the ignition, the column remained locked, but the dash prompts indicated "reduced engine power," "service engine soon," and "low fuel."

I hammered the steering wheel as usual, and the column came free of the locking pin ... but when I attempted to start, the dash warnings remained, and while the engine would turn over, it would not achieve idle.

Fumbling with the DIC, I found that there was a "no comm" prompt as I toggled each system. No codes, just "no comm."

BTW, my battery is a Red Top that appears to be fully charged, and while I have heard horror stories aboutn them, I maintain my battery on a CTEK when I leave it parked for more than a week.

The only other anomaly with the car is a water leak at a crack in the trim strip on the driver's side that has caused the carpet to get wet if the car is caught unprotected in one of the thunderstorms to which we are frequently subjected here in Northern Virginia during the summer months.

I have read tons of posts about this issue, perhaps too many, and I'm left confused and SOL with the Vette. I reckon I need expert help to regain both my mental clarity and my ride before heading up to Carlisle, and hope I can get a permanent fix without having to mortgage my house to make that happen.

So once more, the clues"

1. Locked steering column released by brute force

2. Dash warnings before and after bashing the wheel:

Reduced Engine Power, Service Engine Soon, and Low Fuel

3. Manual diagnostics indicate "No Comm" to all systems

4. Motor will turn over but not achieve idle

Thanks in advance for tolerating this tome and my ignorance of the electronic systems in this car.

 

Just a piece of info.
Your car has not had the recall done.
If your steering wheel still locks it hasn't been done.
When the recall is done they take out the locking plate with the holes & replace it with a blank plate with no holes and then they install a K wire harness relay to send a signal back to the computer that the steering wheel is unlocked. You might need a CLB. Read sticky thread at top for more info

Steve alan

 

Thats not all together true.... many GM dealers just do the computer flash and call that a CLB fix.

 

I'm at it again this morning after charging my Red Top out of the car overnight, got the same symptoms (reduced engine power, service vehicle soon, and low fuel, with "no comm" reported to all systems). The starter engaged three times but the car would not idle, but on the 4th attempt, even the starter would not engage. I'm heading over to Advance AP to confirm the Red Top is not defective.

Corvette Mechanic's response to my post on that site was that the problem with "no comm" is unrelated to the column lock issue I have been dealing with and advises it is time to get it into the shop, which I would have done earlier had I not parked the car where it is very difficult to get to it with a flatbed for the tow to the dealer.

Any thoughts about grounds or other common electrical issues I can troubleshoot before I arrange the tow and turn it over to a real expert?

Thanks in advance for sharing similar experiences.

 

since it is summer and you may be running the a/c, i would check to see if the p side carpet is damp. maybe the a/c udder is clogged and water is dripping on the bcm. i think you have two separate issues. i would install a clb when you get things sorted out. i am not an expert either!

 

You did not say you ever got an actual Service Column Lock error message, so even the column failing to unlock could all be due to a problem with the BCM.
The column lock problem should not keep the car from starting and idling normally. It only cuts fuel when you try to drive it with the column locked.

It does sound like the BCM may be wet.
Have you checked your battery to make sure it is at least putting out 12 volts?

You could eliminate the Column Lock as part of the problem by removing the lockplate and installing a column lock bypass relay.

 

Just back from seeking "expert" consultation:

1. Advance AP load-tested my year-old Red Top, which reported 12.63V, 695 CCA measured vice 720 rated, "meets or exceeds required standards;"

2. Local Chevy dealer Jim McKay shop manager confirms problem is not likely related to column lock issues, probably something in the Class 2 circuit, but he has never seen a car with "no comm" prompts from all the systems reporting on the DIC. He indicated he didn;t know where to start, but invited me to have it towed in (no suprise there).

3. A good friend who ran his own independent shop for 25 years suggested I check the connection between the battery and starter, at the starter, for corrosion or looseness, but he hadn't a clue about whether it would cause the "no comm" phenom if it were ... I'm about to crawl under and see what I can see. My mechanic friend adds that he hates Optimas, and thinks there may be a problem with it even though it load-checks just fine ... I guess you love the Optimas or hate them, but I'm reluctant to buy and substitute a new Interstate or Delco wet cell to confirm his theory, and maybe end up with two good batteries and one dead Vette.

4. The answer to the above question about "service column lock" is "no," it did not come up when I discovered the problem yeserday morning ... just "reduced engine power, service vehicle soon, and low fuel," then the "no comm" warning for each individual system.

5. The passenger compartment is and has been bone dry, and there is no evidence that the OEM battery, which I replaced with the Red Top, had leaked ... all the wiring and surfaces below the battery box are pristine.

6. I pulled the rubber tube off both body to door harnesses, uncoupled and inspected all 4 connectors, found them to be pristine and bone dry, reinstalled and made ready to try again.

Last round of T&E:

With the fully-charged apparently good Red Top back in the car, I inserted the key without attempting to start, once again got the "reduced engine power, service vehicle soon, and low fuel," then the "no comm" warning for each individual system, and after three attempts to start, with the engine turning strong, the engine did not turn over on the 4th attempt.

I am about to check out the connector on the driver's seat, which has the memory feature and has been damp from a water leak over the door ... the memory feature makes this a Class 2 device, and could be implicated, but no one I asked thinks it would cause all systems to report "no comm," even if it were corroded or shorted out.

I'm at my wit's end when even the dealer says "Duh, maybe call NASA ..." so it appears I can't even make it go away by surrendering my wallet to GM.

Any feedback and/or sympathy will be greatly appreciated while I contemplate turning my Z into a plastic planter.

 

CAll ME!!! I have some Ideas.

PM SENT!!

 

That's far from true actually with my recent visit. 8VETTE7 has gone to great lenghts to assist me in my problem. The dealer put a stock system back into my car, refused to perform the recall and refused to cover the cost of the repair. On top of that, they spliced a wire from my BCM and sent it to the relay near the BCM that is related to the theft system. And, apparently removed the K-harness that was isntalled in the car in 04.
8VETTE7 and Bill Curlee are by far the authority on this subject. GM should be ashammed!

 

Hey Dennis,

Sorry to hear of your car woes. I would suggest getting a column bypass kit form Corvettes of Houston and installing that..

Not sure what "U" codes you're getting, but you're in capable hands with Bill.

If ya need anything drop me a PM and I can try to help. I happen to have a Tech2 in my stable of garage tools.

Tony

 

Well, thanks to Bill Curlee's Forum sticky, his assorted posts and several work-day phone calls he took without complaint, I'm optimistic we've isolated my problem to the ignition switch and serial bus, just as Bill predicted.

The last steps this afternoon, after checking the connections at the solenoid and starter, involved jumping the red and purple wires downstream from the TDR relay (located above the BCM in the passenger footwell, and easy to narc out using the pics in Bill's post) with the ignition lock "off," which powered the solenoid and starter just fine but did not simulate starting.

I then repeated the jump with the key "on," which powered the starter and caused the engine to turn over, but not idle, as it should have if the switch were operable ... the logical conclusion is that the faulty switch is interrpupting Class 2 serial bus communication to fuel (and other systems), also resulting in the "no comm" prompt on the DIC, and causing the dash warnings "reduced engine power, service vehicle soon, and low fuel." (Disclaimer: I'm a retired Army officer, recovering lawyer, and shade-tree mechanic without portfolio, not an electrical engineer, and my analysis of Bill's guidance should not be interpreted as gospel.)

In any event, while I've got the dash unbottoned to R&R the ignition switch, I'm also taking Tony's (ajg) advice and installing the CLB from Corvettes of Houston to get over THAT designed-in GM problem ... with guys like Bill and Tony ready to step into the breach using this Forum, even a bad day with a Vette coming up DOA in the driveway may not the end of the world.

 

See that,,,,and you were ready to burn the car! Glad your back on the road! How bad were your switch contacts?????

See ya at Carlisle!

 

Hey Dennis glad you got it all figured out with Bill's help.

When you install the column lock use a piece of velcro to adhere the litle black box to the metal bracket under the steering column and not double stick tape, that way if you ever have to get back in there it will be easier to gain access as the wire leads are very short.

 

Thanks to all for stepping up with comments, tips and solutions ... I'm at the under-the-dash phase, upside down, feeling like Jonah inside the whale ... looks pretty grim with all the plastic off, not quite like the go-cart step building my bud's FFR Cobra replica, but pretty unsettling to contemplate the guts of the Z, even with light at the end of the tunnel.

BTW, good tip from Tony about Velcroing the CLB into place, and another round of thanks to Bill, who dropped me a note last night offering me the reassurance I needed to get upside down and sideways again this a.m. hoping to get it back on the road later today ... I was about to blow off the project for a day to hit the twisties on my bike, but I'm pumped to get the surgery done without further delay. Hopefully the next post will confirm there is life after no start, no comm.

 

Back on the road via Bill's ignition switch R&R ... FYI all, the following codes dumped out of the DIC as she idled ... anyone's analysis or feedback would be appreciated, even though I am "whole" again.

BILL'S THE MAN!

PCM P1626H

TCS U1301H
U1000H

BCM B2587H
B2592H
U1255H

SDM U1301H

IPC U1255H

RADIO NONE

HVAC U1064H
U1096H
U1160H
U1255H

LDCM B2282H
B2284H
U1064H

RDCM B2283H
B2285H
U1064H

SCM B0851H
U1300H
U1255H

RFA U1255H

 

They are all history codes.

Clear them out.

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
3. Press and hold "options" and
4. While holding "options", press "fuel" four times within a 10-second period.

For each module, all DTCs will be displayed. If none are present in a module, you will see "no more codes" on the ICP display.
There are two kinds of DTCs, "Current" and "History," designated with a letter suffix, "C" or "H". A current code indicates that the malfunction is present in the system whose module is displaying data. A history code indicates a problem existed in that module sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it is possible it's evidence of a previous problem, now solved, that was not removed by clearing codes. More likely is that a history code indicates an intermittent malfunction. "Intermittents" are the most challenging DTCs. An intermittent may have happened only once, may have happened more than once but is inconsistent in its appearance or may be happening on a regular basis but not at the time the IPC is displaying codes. History codes can also be caused by a current malfunction in a system that is not operating at the time DTCs are displayed. An example is the rear window defogger which doesn¹t operate until the BCM detects engine rpm. For history codes set by a system 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 IPC has displayed all 11 modules, the system goes into the manual mode which allows selection of each module using combinations of DIC buttons. The manual mode can also be entered at any time during the automatic sequence by pressing any button except "E/M". Once the IPC displays "manual diagnostics," you may select a particular module by pressing the "options" button to go forward or the "trip" button to go back. Once a system is selected and a DTC is displayed, if more than one are present; press "gages" to move forward or "fuel" to go back.
To exit the diagnostic mode at any time, press "E/M". If you want to erase or "clear" codes, press "reset." Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory.

 

After several days of "normal" operation without codes or dash warnings, and after a Saturday of torrential rainfall here in Northern VA with the car exposed in the driveway, upon start-up this Sunday a.m., which was accomplished smoothly and without the symptoms of the past week, I found these codes on the DIC and cleared them:

IPC U1255H

LDCM U1064H

RDCM U1064H

A6SCM U1300H

I know the IPC and (L/R) DCM codes are related to communication on the serial buss, which when this episode began was central to my no start situation, but the SCM code on that loop on the buss once again seems to me (not a GM pro by any means) to be the culprit ... my driver's side windshield seal is not yet fixed, and the carpet under the seat was saturated after more than an inch of rain yesterday, so I'm wondering if the U1300 code at the SCM indicating "Class 2 circuit short to ground" is where I need to focus ... obviously, I need to fix the windshield seal, which I plan to do in conjunction with some paint work on stone nicks on the hood and front fascia, but I'm looking for reassurance or shared experiences that will encourage me this may solve my problem.

Bill Curlee is on the case (thanks again, Bill), but anything I (we) collect in the way of in-the-driveway anecdotes or shop case studies posted here will serve to help me and others who have been there and solved their problems without defecting to Toyota and trading their C5s for something like a Prius.