Hey CorvetteForum and all its awesome members. I have a 1998 Corvette base model convertible. It wont start.I turn the key the dashboard cycles normally, i hear the relays on passenger floorboard yet when i turn to start it wont engage the starter, Ive read forum after forum and already replaced so many parts. ill list the parts ive replaced as to eliminate a lot of questions.

New battery
New starter and New starter wires all heat shrink-ed and perfect
New ignition swiotch
No aftermarket radio or any other aftermarket item
Theft system works fine and is not the issue. My light goes out after inserting key and i hear the beep. (Ive already tried bypassing the TDR with the 7.5 resistor doesn't do anything)
Ive also jumped the red and purple wire at the theft relay(new relay installed old relay tested ok)
Ive put the multimeter on everything looking for a parasite draw and dont find one.
Ive put multimeter and test light on every fuse
Ive done everything these forums are telling me.
Key fobs and keys all test perfect according to charts


Here is something i found odd. If i take a screw driver and jump the starter it fires right up but then dies. im going to try and turn the fuel pump on manually to see if it stays running.

 

You mentioned jumping the red and violet wires at the TDR ,did that energize the starter? If the starter does not energize it means that there is either no 12v on the red wire or there is no continuity from the violet wire at the TDR and the starter solenoid terminal.

 

So what do I do?

Put a multimeter on purple (with and without key turned on. ) is that correct

 

You can put a multimeter on dc volts and place leads on a ground and the red wire at the TDR it should have battery voltage regardless of the key positon. Measure the voltage between the violet wire and ground with the switch in the start position you should have battery voltage.

 

Ok the red wire reads 12.54 volts with key on and with key off
The violet wire also has voltage with key on and key off

 

The red wire always has power regardless if the Ignition switch is off or on, the key doesn't even have to be in the Ignition switch. The violet wire should only have voltage when the Ignition switch is held in the start position and the TDR has been energized. If there is 12v on the violet wire it should energize the starter because it is the wire that connects to the starter solenoid terminal.

 

So I guess I follow the plviolet wire and see where it's getting voltage from

 

What do you mean "has voltage" ? Are you saying there is ~ 12+Vdc on the purple wire with the ignition in the off position? If so, I would double check your connections at the starter solenoid. Make sure the purple wire is connected to the "S" terminal (as shown) and nothing else is connected to that terminal. Take a pic of your starter connections and post if you are unsure.

Photo courtesy of the the Master.......Bill Curlee....

. Make sure the purple wire is connected to the "S" terminal (as shown) and nothing else is connected to that terminal.

 

Let's attempt to understand how the starting circuit works, eh? (see attached)

We should have battery power on the red wire that goes to the ignition switch.
When we turn the ignition switch to the start position, the red wire gets connected to the yellow wire via the ignition switch,
Power on the yellow wire is connected to the purple wire via fuse 14. Is this fuse OK? Do you have power here, when the key is turned to the start position?
The purple wire goes to the Park/Neutral switch on the side of the transmission (or to the clutch pedal switch with a manual transmission). This switch interrupts this circuit, so that you can not start the car unless the transmission is either in the park, or neutral positions. This switch will need to be bypassed, since it has been removed from the car, along with the transmission (jump the purple wire to the yellow wire).
The yellow wire energizes the Theft Deterrent Relay in the passenger compartment fuse box. When the key is turned to the start position, does this relay click? In other words, is there power on pin C2 of the relay, with the key in the start position?
In order for the Theft Deterrent Relay to energize, it also needs a ground on the yellow/black wire. This ground is provided by the BCM if the appropriate conditions are met. Is the BCM providing this ground when the key is turned to the start position?
When the Theft Deterrent Relay energizes, it connects the power from the red wire to the purple wire. Note that this is the equivalent of jumping the purple and red wires at the starter motor, itself.
With power on this purple wire, the starter solenoid should energize. Note that the started solenoid is similar to a big, heavy duty relay. Among other things, when the starter solenoid energizes, it connects the big red power wire on the starter motor, to the internal windings of the starter motor, causing the starter to crank the engine.

With a helper to operate the ignition switch, I find it convenient to remove the Theft Deterrent Relay and test with my Volt meter to see what I am missing. You should have power on the red wire at all times ... power on the yellow wire with the key in the crank position ... ground on the yellow/black wire with the key on the crank position ... and ground on the purple wire, with the relay removed. With the key off and the Theft Deterrent Relay removed, if you jump the red wire to the purple wire, the starter motor should crank, but the engine will not start and run (because both the fuel pump and the ignition system will be disabled).

Let us know what you are missing at the Theft Deterrent Relay and we can proceed from there.

EDIT: I should have mentioned that having 12V at any given place in a circuit is not a guarantee that the circuit is in good working order. Yes, we need voltage (electrical pressure), but we also need amperage (electrical current flow). A volt meter only measures the electrical pressure in a circuit, A test light with an conventional incandescent bulb (NOT a LED!!!) can quickly determine that circuit's ability for current flow.

 

Ok I had the violet wire touching the other wires. That has been resolved. So here's the new symptom


Redwore at TDR has 12 volts
Violet wire has no volts. If I touch the two together the starter engages and tries starting the car. The car starts then shuts off

 

Good, that's what I figured

Why not just try to start the car normally with your key?

 

Presumably, nothing happens when you attempt to start the car the old fashioned way ... with the key. Going back to my previous post and assuming that you have a jumper wire in place of the transmission selector switch, when you turn the key to the crank position, what is missing at the TDR? Are you missing power on the yellow wire, or are you missing the ground on the yellow/black wire, or are you missing both?