SqueakJohnson

I really appreciate all your help!

mmartinez

Your Welcome

RoadkillTrucking

What is the TDR and where is it located???

Smoken1

Theft deterant relay and it is in the passenger side fuse box

mmartinez

To poster #23, please read the entire thread as I explained how to use a multimeter to measure voltages at the TDR.

SqueakJohnson

Alright I'm back. No crank again. No codes. Tried park and neutral. Replaced battery. Replaced TDR relay. No security light. If I jumper the red and violet wires, it starts and runs without issue, security light does not come on, goes out like it should. I do not have 12v at the yellow/black wire with the key on though. I've replaced the ignition switch, ignition cylinder, keys, battery, TDR relay, still having the same issue. Could it be the new ignition switch? What do I check next?

SqueakJohnson

I pulled the ignition switch. Two contacts had slight burn marks. All the tabs were loose. What a mess. Sanded contacts, bent everything to add tension, reinstalled, connected battery, started right up. I feel like there have been times before though where I've disconnected the battery for at least 30 minutes and it'll start up after reconnecting. I'm about to disconnect in order to out everything back together fully. Hopefully this solves my issues. If not I'm just gonna set it on fire.

lucky131969

So if you are back probing the TDR connector jumpering contacts c1 and a2, and it runs normally, then it suggest the TDR is not working. Do you hear a click when trying to start? When trying to start, is there 12 volts on C2 of the relay connector, and a ground on A1 of the relay connector?

SqueakJohnson

​​​​​​Sometimes I do, sometimes I don't. Before I pulled the switch today, I did not have 12v on yellow/black. After pulling and cleaning/bending tabs in ignition switch, starts right up. No security light, no codes.

mmartinez

Remember that yellow black stripped wire is a ground being provided by the BCM, you have to use a 12v supply from a fuse for the other meter lead.

lucky131969

...with the TDR plug disconnected, you wil should have a GROUND on the yellow/blk wire at contact A1, and 12 VOLTS on the yellow wire at C2 when you try to start the car.

donjetman

Sounds to me like a Vehicle Anti Theft System = VATS problem.

99% of the time my 02 auto coupe would start no problem. But 1% of the time when I turned the key ON the security light would stay lit and when I turned it to START it would not crank, Nothing. Some months previously I had changed the ignition switch and TDR theft deterent relay in hopes of fixing this problem.

This time I'm doing the VATS bypass fix.

I ohmed my key = 11.80k ohms (#15), watched "vetonvetts757" utube video, ordered amazon resistor kit $13, soldered a pair of these resistors together that equaled came close to matching my key (11.90k ohms), put heat shrink on it, and installed it at the appropriate two pins/wires at the BCM in the passenger side footwell.

I went to a local old school hardware store with old school key cutting machine, picked out 2 blank GM double sided no resistor/pellet keys, and had them cut to match my original key, $9

Got home and both my new to me no resistor/pellet keys work great. The original resistor/pellet keys don't work. They would if I cut/disconnected the resistor sensor, either at the key/ignition switch or the bms in the pass side footwell.

He's one of many videos about this problem:
and

SqueakJohnson

Ever since I opened up the ignition switch, I have had no issues starting the vehicle. I haven't checked anything else since reinstalling it all and I don't want to since it's working haha. But I will eventually be back in thee since I only get heat on the passenger side.

donjetman

I thought I had fixed mine too after changing the ignition switch and TDR many months ago. Then last week it did it to me again

I'm hoping this VATS bypass fix really is the fix.
Good luck

*NOTE* I did clean the contacts in my original ignition switch and I'm keeping it and the original TDR as spares.