I had a reputable Vette shop r/r the dash ign switch bc the “security “ light would illum. Read about the VATS. Bought a new key before the shop got Val.

r/r fixed the VATS issue but now when cold (<~50) no crank.

Val has Already been back to the same shop and replaced the starter. Thought it was fixed. But this AM. OAT 45. Again no crank. Sigh.

suggestions?

Considering a push button start.

thx

 

Clutch pedal switch?

 

thx. Will check that

 

Will you be doing the diagnostics or your shop ??…with the cold being the factor we can possibly guess it’s a poor connection somewhere because when it’s cold metal contracts so there is your poor connection…if you have a 12 volt test light, a DVOM, and maybe a jumper wire that would help if you are going to attempt a fix !!…I think it would be more of a connection on the outside of the car and also make sure your battery is in good shape..12.66 volts being a fully charged battery and I would have it load tested…also make sure you diagnose with a battery voltage of at least 12.45 volts. If you want to try something quick and you have jumper cables connect one end to battery negative and the other end to a clean spot on the engine block or if you connect a 12 volt test light to battery negative and when trying to crank the engine while probing a clean spot on the engine block if the test light illuminates you have a bad ground. Does the security light go out when you turn the key to on after a few seconds ??

 

yes the sec light extinguishes aa it is supposed to do.

the battery is in good shape … load checked.

will check the clutch pedal switch next.

…. any problem with just bypassing that … or will a continual “clutch pressed” signal cause other problems?

 

For safety reasons I’d replace it if bad…you don’t want to accidentally leave it in gear with the clutch not depressed when starting but that is up to you !!

 

Right ...

but there aren’t downstream effects in the BCM ... or something completely unrelated (door locks?) which will malfunction with such a configuration? The only result is “be careful” when starting?

I was raised on manual trannies ... and I’m the only driver of Valerie. If replacing this thing doesn’t fix it, then I’m bypassing it.

the easy entry mode of the seat makes clutch pedal pressing problematic when not in “drive position.”

Thanks for your help! I’ll update later this week as I had to leave town by driving the dually to the airport vice Valerie.

 

Bypassing the switch if it is the cause will have no effect on anything else that I can think of…if this doesn’t fix it keep us updated and we are sure we can get you back on the road !!

 

i have ordered a new clutch pedal switch (cheap) ... and another ignition switch. GM parts.

Arrive on Thursday ... so ... project on Thursday. Thanks.

And I apologize for the duplicate thread. When I was searching earlier today, it was on my mobile device and ... well ... I’m Johnny Lawerence without the roundhouse kick.

 

In your initial post you said the ignition switch was replaced so to save you from possibly replacing a good switch some basic voltage drop testing with a multimeter can be done to verify it’s not the switch…if you have a multimeter and want to try this let us know so you won’t be firing the “parts canon” !!

 

Yes ... I will do that, too, as I get into it on Thursday. Will search YT for some how-tos. I’d like to avoid breaking the console cover. It IS 20 years old after all.

The service writer did advise I’d apparently bent the clutch switch bracket during my autocrossing ... but I had the first indications of this problem that very morning (before spirited driving)

I replaced the original ignition switch because of the VATS issue ... and I was concerned it’d “lock out” the starter.

kinda like what is happening! SMH.

will roll the acorn s’more. Thanks C5!

 

The VATS and the ignition switch are really 2 different systems…was the ignition key lock cylinder replaced as well ??…here is a YT video but I’d do some detective work first !!

 

no the key lock wasnt replaced.

thanks for the vid!

 

I took Val back to the shop yesterday. from the start of this thread ‘til yesterday, my weekend got full.

Will update this thread with findings/action .... and whether we appeared to be successful.

 

spoke with Chance today. Looks like I may have received a less than good ignition switch. Temps are supposed to be in the 50s tomorrow AM and we'll see what she does.

He reported that on one occasion she shutdown when in reverse and asked if that'd happened to me. Maybe. I thought I stalled it, though.

Hopefully this is it.

So parts is a thing. Had to warranty a Tempken Right Rear hub bearing assy. Also ... related only by parts; I was a gomer and left my locking fuel cap on the flat bed of my dually this weekend. had to call 3 parts stores when I was in San Antonio to get a replacement.

 

report yesterday was ... "my" ignition switch installed. Initially worked well. Then it failed again.

Going to install a bench checked BCM and see if my BCM is malfunctioning without throwing a code.

mercy.

I'm getting a lot closer to a starter mod ... a switch panel where the ashtray was originally ... USB ports ... and a "hot battery" push to start button.

 

I wouldn't think a mechanical switch would have a temperature related intermittent problem.

Batteries are effected by temperature, and your battery might test very differently in the cold conditions you say are the only time this happens, and the only consistent variable in the systems mentioned. I mean no offense if you already know this stuff, I don't pretend to be highly skilled in corvette repair.

Before flashlight batteries improved, it was somewhat common knowledge that a dead battery could be used a bit longer by heating it in the oven, the increased temperature "goosing" the voltaic reaction. Colder temps decrease the reaction. I hope your problem is just a tired battery, I don't think temperature would effect the function of the BCM. In the reports I have read, it is either broken or not, nobody has ever said anything about intermittent function as a condition of temperature, and I hope you are not the first. With the testing these designs go through before being sold, I would think a temperature related functionality problem in the BCM would have been caught and corrected.

I try to avoid buying parts without a solid understanding of what is the problem, but have had one or two educated guesses work out, usually on machines not nearly as complicated as cars. If I see a professional throwing parts at a problem, I hire a new professional.

Having the car stall in reverse certainly complicates things, since the starting circuit is not the run circuit. Your original complaint was intermittent starting, but with an intermittent problem also in the run circuit, you might have a intermittent connection behind the dash. I had this problem with my convertible, where enough people had been screwing around with the anti theft system that a connector on one of the " fixes"got a broken wire, and once in awhile, went on vacation.

 

Appreciate your sensitivity to ego ... but mine's not that forward.


I'm the guy throwing parts. I was just convinced I got a "not fully ready to go" part. We'll figure it out eventually, but I sure thought it'd have been by now. Did a requested ignition switch change over a month ago to avoid VATS shutting me down ... and now I've got this intermittent cranking failure. UGGHH!

I told the service writer getting stranded at home is better than being stranded in the parking garage at midnight/twenty degrees F ... 1+35 from home.

I expected to put some money into this 20 year old car to make/keep it front-line drivable ... I just didn't' expect the pros to be stumped.

 

An occasional no cranking problem is really not hard to troubleshoot, but it does require voltage measurements. In a nutshell this is how the starter is enabled, voltage leaves the Ignition switch and is wired to the clutch safety switch where it is then wired to the TDR that's the relay that sits on top of the BCM. The Ignition switch contacts that press against the keys resistor pellet cause a signal that the BCM recognizes as the correct key, the BCM then switches a ground to the other side of the TDR coil. The TDR when energized sends power to energize the starter. TDR has four wires, yellow and yellow black strip wires are the positive and negative relay coil wires, the larger gauge wires are red and violet which are
the connected across the relay contacts.

 

thank you sir.

I'm gonna wait & see what the shop finds. I've since found a couple other threads on this and this TDR hootus seems to be a potential problem, too. It's just weird how this condition appeared AFTER I had the ignition switch pre-emptively changed to cancel the solid "security" annunciator.

This entire deal seems far more complicated than it needs to be. VATS/PASS/TDR/BCM ... MOUSE. mercy. This increases horsepower/torque/handling how? :P

... then there's the recognition, these cars were supposed to be in the scrap yard 10 years ago.