Question 96 Camaro Z28 doesn't crank?

[kyle1559]

I've got a 1996 Camaro Z28, the person I bought the car from, had messed with some of the electrical harness's before I believe. Occasionally i will go to start the car, and it wont crank, all the dash lights come on, radio comes on, and when i turn the key, all the lights dim, and the volt gauge will drop. let off and everything comes right back. Now when i turn the key on the fuel pump does prime the system. I can see that the person before me had probed the purple wire going to the starter solenoid multiple times. i can take a piece of 12 gauge wire and put it through the hole in the purple wire, and touch it to the battery and the car will fire right up with no problems. What could be the problem here? a break in the wire somewhere?

[cocobolo95]

The problem could be the vats security system or the electrical part of the ignition switch. Unlike older cars where the start wire from ignition switch went directly to starter solenoid, these cars the trip is very complicated. From the ignition switch the wire travels to the tdr (theft deterrent relay), to the transmission position switch or clutch start switch. It has traveled through a splice, several connectors. The purple wire that goes to solenoid comes off the tdr. shbox.com has a starting and charging wiring diagram on his site. 4th gen section has the 96 f-body service manual to download. Manual has complete wiring diagrams, troubleshooting guides for your car.

First thing I would check is if battery voltage is coming out of electrical part of ign sw on yellow wire at connector 2 cavity A when ign sw is in start position. That will let you know if ign sw is the problem.

If ign sw not the problem, then wiring, connectors, safety switches, splice, or tdr could be bad

[kyle1559]

oh, i also forgot to add that we have replaced ignition switch, on the top of the column, and the clutch safety switch down by the clutch, it is a 6-speed manual. Where is the Theft Deterrent Relay? Because it isn't in the fuse box under the hood.

[cocobolo95]

Tdr is tucked up under the right side of dash near the sir bracket next to glove box. It's right next to hatch relay. To make sure you have correct component, tdr has 4 wires; large yellow, large brown, large purple and small yellow/black.

The tdr works like this. Relay is made up of 2 parts-(1) relay coil and (2) relay points. Both relay coil and points get battery power. So large yellow wire at points and large brown wire at relay coil should have battery voltage with ign sw in start position and clutch pedal pushed in. The yellow/black wire of tdr coil supplies the coils ground from bcm. This is if the key used is correct one. With the power from clutch switch and the ground from the bcm- the tdr points close and power goes out of purple wire to starter solenoid.

[kyle1559]

I've found the relay, pulled it out, had my dad get in, push the clutch in, and go to start it, both the White, and brown wire, had 12v. I plugged relay back in, and it fired up. Now normally it will run fine for a couple weeks, months, whatever it feels like doing. Then its right back to not cranking. So, maybe the points inside the relay are wore out? So ign sw, and clutch switch are good. its somewhere between the relay it self, the purple wire in the connector, the purple wire itself, or the solenoid it self. Which i think is very unlikely because we can jump the purple wire to the battery and it starts. and the starter+solenoid is less then 7k miles old. If you do believe its the relay, where would i get a brand new theft deterrent relay?

[cocobolo95]

GM part # 12193601 most any GM dealer should be able to get it for you. www.partszoneonline has it at a discount $26.45 plus shipping.

However, if you don't mind changing connectors to hook to relay, a standard 30 amp relay sold at any parts store can be made to work, at about half the price. Thing to remember about standard relays is their markings. Terminals 85 & 86 are for relay coil, while terminals 87 & 30 are for relay points.

[kyle1559]

Alright, this has really narrowed down the possible causes of what this could be, Thanks!