Just got my first vette. 2001 c5 a4 vert. With 70k miles. Drove it all summer never an issue(7k miles DD). Now the temp has dropped here in NJ no start issues, Everything comes on with key,fuel pump, lights etc. Go for start, car goes dark and nothing no crank at all, let go of key everything on dash lights back up. Replaced key (no security light), ignition switch (started up after replacing), TDR cause it was cheap enough, new dekka battery (3months old). Checked grounds and fuses all good. Cars never seen salt or a leaking battery. Sometimes it starts after flicking lights on and off and or rowing through prnd,tapping starter, leaving it sit in the sun, or cursing at it, but all stopped working now. I also seem to have a magic battery drain to. Sitting over night in my garage(bout 7hours) the dash readout now says 11.4 volts smh. Mods on car are basic SE headers,cat delete nxt exhaust,vararam intake and a tune. And yes after tune car ran great.
codes on dash are
IPC- u1176h,u1064c,u1016h,u1040h,u1088h
radio- u1064h,u1016h,u1096h
There is so much information on this issue I don't know where to start, anyone got a direction to look in.

 

Welcome to the Forum !!…well how good are you with a DVOM ??….since you have a battery drain I’d start there…I’d fully charge up the battery to 12.66 volts (your 11.4 volts is basically a dead battery so it’s probably not going to even crank over) and start your troubleshooting…this drain may lead to your no start condition…video below so as you’ll see the voltage drop method is better than pulling fuses…video below. You can also remove the B+ cable from the alternator…a failed diode can cause a drain…also, having the no comms with the IPC and radio I’d look at fuses 25 and 19 (IP Fuse Block) and for the radio fuses 5 and 24 (IP Fuse Block)

 

yes 11.4 volts is dead i believe the lowest that will start a vehicle is 11.7 volts according to a battery auto disconnect inline with battery cable with auto disconnect at 11.7 volts if lights left on so the car will have enough power to start or if there is a parasitic drain somewhere with the car off.

 

So 1st, sorry for the week late thanks ya guys on quick answers and starting points. Update on everything. I post my issue get home from work. Car starts every time with out fail. Battery maintained 12.4v over night. Used the car every day to and from work (60 miles round trip) . Yesterday it gave me a new weird issue, typical no start problem, letting go of the key, as the key returned back to acc, the car would cough. Weird. Did that 2 more times, no start, cough from engine as key returns back to acc. Then it just started like normal. This morning, grab the newly acquired multimeter, check battery 12.35v. Sweet deal, go to start and nothing, everything turns on go to crank just black and silence. Seems it's temperture sensitive(frost and 30ish this morning). Even though car is stored in garage. Guess that means I'm gonna learn how to use a multimeter and start tracing where I'm shorting/losing power. Figures my first vette car is so much fun and I bought a headache lemon

 

Very first thing to do is place multimeter leads across the yellow and yellow black strip wire at the TDR socket. Have someone turn and hold the key in the start position the meter should read 12 volts and you should hear the TDR click on. One other thing to do is place a short wire jumper between the red and violet wires at the TDR socket, doing this bypasses everything and sends power to energize the starter, extreme caution when doing this, make absolutely sure that the car is in Park, if it cranks over everytime it rules out the starter as the cause of your cars no crank problem.

 

Didn't expect a go try this idea do quick. Ok cool thank you. As soon as I get home from work I'm gonna try that. I'm willing to bet when I get home and try to start its going to fire right up since the outside temp came up.

 

Martin,
Correct me if I'm wrong but with the key in start wouldn't you see 0 volts on a DVOM if the starter enable relay closes ??...if the relay didn't close you will still see 12 volts...12 volt "potential" across the 2 terminals...12 volts on one side and 0 on the other...no ??

 

The TDR is a relay, it should have 12v on one side of the coil and negative/ground on the other side of the coil in order to energize, is that not correct?

 

Yes, it will have 12 volts on the feed side and 0 potential or ground on the other for any relay…when checking with a DVOM you will see 0 volts whether on the load or feed side once the contacts close….take some thin copper wire or any thin wire if you have some and wrap it around pins 87 and 30 or 85 and 86 and reinstall the relay…place your DVOM leads on each wire and read the voltage when the relay is energized…see what you have.

 

I am not talking about load or feed side of the relay contacts, I am saying that you should see a difference of potential across the TDR coil. I just went into my garage and connected a 12v relay to a rv battery and measured 12v across the relay coil.

 

Yes !!…that is what you will see !!

 

Ok, so I gotta say thanks to everyone for responses and go to. Finally got free from work to play with it...checked grounds, relays,jump starter, check connections etc. All seemed normal... friend suggestion,checking the brown wire on bottom ignition switch, he remembers seeing something off when we changed out...suggested push the wire up,maybe it's losing contact. turn key fires up everytime. Repeated 5x in cold weather. Just gotta fix that loose connection.

 

Update...Well I thought that was issue, car ran great yesterday, leave it parked outside to test the cold theory. Welp...no start, drop that panel under steering wheel start pushing on wires. Fired right up 2x. So now gotta figure out what wire in that plug is giving me the issue, but at least it seems it's isolated.

 

Yup, perhaps 1 wire is just a bit short, maybe only 1/8"-3/16", or the female pin may be over expanded for whatever reason. Anyone whos ever owned British motorcycles, or cars, knows about Lucas (You Cuss!!) electronics. I had a 1970 Norton 750 Commando that was the score of my lifetime. Won first place in a bike show. But it didn't run. Had only 2,100 miles on it, and looked it. Carefully watching the ignition switch, I saw a spark whenever I turned the key. Sure enough, one stinking wire was not quite long enough. Stretched it out a bit, plugged it in, PRESTO-Bike fired right up! I paid just $2,500 for it. When I listed it-sold it for a considerable profit-I had calls coming in from all over the U.S.!! I'll bet it is only one stinking wire......

 

That's what I'm hoping for, cause the switch is new, everything checks out good...still very weird it happens only when below 40. But jiggle jiggle those plugs and it fires right up smh. Hopefully I get it fixed before weekend. With all the parts and tune I want to get to the track at least one more time.

 

Got it!!! It's not an individual wire. The entire plug has an extreme amount of play, causing the wires to lose contact

 

Colder tempathures causes metal to shrink, while warmer temperatures cause metal to expand, that is why your car is experiencing no cranking problems in cold weather. I belive that the connector that plugs into the Ignition switch has loose fitting contacts and they need to be addressed.

 

Yes sir that's the problem, cold weather shrinkage. If it doesn't start wiggle the entire plug push up and good to go. I wonder if the ignition switch is made to a different tolerance or the plastic plug body is worn. I can't see all the pins being worn but who knows. It's clear someone else was there before I got the car.

 

That plug must be going swimming when ur not around. Reminds me of A show called Seinfeld.

 

I was in the pool. What a great show