ok so I am diagnosing a no crank/no start condition on a 92 RS at my work. Battery is good. Turn the key...nothing, no crank. I jumped the starter and it works. I turned the key to on position, jumped the starter and it cranks, I spray carb cleaner in and it sputters like it wants to start but doesn't.

So I dive in and check to see if the starter enable relay is getting power from the ign switch. According to the shop manual schematic the relay should have a pink wire from the ign switch, yellow wire from the ign switch, dark green wire going to the shifter selector switch and the black/yellow wire to the VATS. Ok so I find the starter enable relay and noticed there is no pink wire but a white or faded yellow wire of small gage like the black/yellow wire. I got the rest of the colors correct but no pink wire. Schematic shows pink wire from ign switch to relay. Can't seem to find where this mystery wire goes. Right now the start enable relay is not getting power to the relay, so I don't know if the VATS is grounding the black/yellow wire, nor do I know if the VATS module if bad.

I bypassed the start enable relay and got the eng to crank with the key but still won't start.

Does anybody know what that white wire is where a pink wire should be? I'm about ready to re string the circuit so it matches what the schematic shows.

This pic shows the relay connector and its wires. So according to the shop manual that small gage white wire should be pink??? everything else matches. There is no power with the key on so the relay is not being energized. I can jump the yellow and green wire and it cranks with the key but won't start.(the pic I borrowed from another post and the wires in my car are not cut like that.)

The black/yellow wire is from the VATS, it supplys the ground for the relay.

Any comments/advice would be greatly appreciated, thanks!!!!

P.S. can you get to the VATS module from underneath the dash or do you have to take off the dash cover???

One thing I noticed is the "security" light does not light up, could be a burnt bulb or a hint of a faulty VATS module???

 

Ohm checked the key cylinder with the key in it and got infinite resistance. Checked the key itself has 7.50kohms. Gonna replace the key cylinder tomorrow see what happens.

 

Let us know what you find out.

 

The Starter Enable Relay used to have a yellow thin wire instead of pink before 1992. You might have a 1991 wiring harness that is faded a little so it appears white.

If you get infinite resistance from the key tumbler, the contacts are likely worn out and done for. Did you measure it on the actual tumbler or the wires that come out of it? If on the wires, the fault might be in those too.

Let us know what you find.
Lou

 

So yes the car was built in 10/91 so that makes sense about the wire color.

So after finding open resistance in the ign key cylinder I took apart the steering wheel and BINGO found a broken wire at the cylinder. Installed a new ign key cylinder and new key and she starts right up!! The security light now works properly.

Lesson learned, the start enable relay gets energized and closes the contacts to send power to the starter only when the VATS module sees a valid key signal, then sends a signal to the ECM to enable the fuel pump and pulse the injectors.

 

All previously documented
https://www.thirdgen.org/vats_passkey_system

 

A minor correction to prevent misinformation from spreading (it happens fast):
VATS does not control the fuel pump. It only disables the starter and injectors.

Congratulations on the troubleshooting and the right fix!

Lou

 

Yes I stand corrected. Only enables the ECM to pulse the injectors. The diagram in your link makes more sense vs the '92 shop manual. I see now the small yellow wire from the ign switch to the enable relay only gets power during crank operation, not key on eng off. Learn something new every day.