Maybe Clutch Switch?

[TX '90 ZR1]

Drove the car a couple of days ago and parked it in the shop. I needed to move it to a different area so jumped in to start it. Nothing. Never had an issue before with starting.
Battery is full charge, security appears to be OK. When I turn the key to start position, the radio and AC control displays dim. This happens whether I have the clutch pushed down or not. Verified full clutch pedal travel.
I'm starting to do my FSM research and also checking the threads here. Just thought I'd throw this out for ideas from the knowledegable people here on the forum.
Oh, it's a '90. 35k on the miles.

[jss06c6]

How old is the battery? Do you have a charger that you can use? To verify a good battery requires a load test, not just a voltage check.

Sent from my XT1585 using ZR-1 Net Registry mobile app

[Paul Workman]

Well, the starter makes a pretty good impromptu "load tester". Anything under 10 VDC across the battery terminals after 10 sec of cranking WHILE cranking = weak battery and the charging system (if and when the car starts again) should be checked to see approx 14.7 volts (cold engine and discharged battery).

From a paper by Marc Haibeck, (below) the 90-92 starting schematic WITH typical voltage readings at the various test locations. (See ZR'1 Specialist for complete article)

AND, a schematic of an auxiliary start relay modification that can be installed to relieve the high current load (and subsequent high wear rate) of the clutch safety switch.

[TX '90 ZR1]

Originally Posted by jss06c6

How old is the battery? Do you have a charger that you can use? To verify a good battery requires a load test, not just a voltage check.

Sent from my XT1585 using ZR-1 Net Registry mobile app

Battery is less than a year old. Load tests good. Hooked up charger on boost and still same results.

[TX '90 ZR1]

Originally Posted by Paul Workman

Well, the starter makes a pretty good impromptu "load tester". Anything under 10 VDC across the battery terminals after 10 sec of cranking = weak battery and the charging system (if and when the car starts again) should be checked to see approx 14.7 volts (cold engine and discharged battery).

From a paper by Marc Haibeck, (below) the 90-92 starting schematic WITH typical voltage readings at the various test locations. (See ZR'1 Specialist for complete article)

AND, a schematic of an auxiliary start relay modification that can be installed to relieve the high current load (and subsequent high wear rate) of the clutch safety switch.

Paul, not getting any clicking anywhere like it is trying to engage the starter. Same result w/ battery charger on boost. Battery load tests good.
I have never noticed, but is is correct for the radio and AC display lights to dim when turning the key to start position? Mine are dimming either with the clutch pedal down or not.

[TX '90 ZR1]

Got started troubleshooting. Here's where I am and need ideas.
With key in the start position the security light stays on steady. According to Marc's troubleshooting write up, this indicates the VATS system is shutting everything down.
Checked codes and get a big H53 after a small 1.-(nothing after the 1.)
Also get a big H46 after a small 4.-(nothing after the 4.)
Went to the FSM and code 53 has to do with the pass key. Followed instructions to read value as instructed in step 1. The number I get is 255.
After this I am getting lost. They are mentioning an adapter from J 35616.
I see no reference to code 46 in the CCM section. Code 46 in the ECM section refers to injector shut down. Could this be what I am seeing?
Anyone have any ideas or input?

[TX '90 ZR1]

Did not get to spend a lot of time on it today.
Here's what I did accomplish.
Checked ECM codes and am getting a #46 which refers to the pass key just like the #53 on the CCM. This tells me the issue is definitely in the VATS system?
Tried second ingnition key, but still same result.
Will try to get time over the weekend to figure out the additional troubleshooting steps in the FSM.
I'll post what I find, but still open for suggestions.

[Flyman 27]

The wire from the key switch which carries the key code (resistance) to the VATS system is fairly fragile. It is the orange 2 lead wire. You can check the resistance between the 2 leads on the plug at the harness. It is on top of the lower steering column. This will tell you quick if the key switch is working. Cycle the key switch while checking the resistance.

[QB93Z]

You said that the with the key in START, there is no cranking but the interior lighting dims. Is that correct?

To me that indicates that the starter circuit is energizing the starter coil, but the starter contacts at the coil are not energizing the starter motor. If VATS or clutch switch was not correct, there would be no voltage drop with key in START.


Although, the Codes you are getting are curious. Have you tried push starting the car?


Jim

[TX '90 ZR1]

Thanks for the input guys. Any other thoughts would be appreciated.
To sum up the scenario:
Car was driven 5 days ago. Everything working correctly. Made several stops with normal shutdown & restart. Return to shop and park car. After sitting 2 days unlocked with key out of ignition, car does not attempt to start.
Security light blinks with car at rest w/doors unlocked. (Normal)
Set security system and simulate brake in, horn sounds. (Normal)
Insert key in ignition switch and turn to "on" or "start". Security light goes to steady and does not go out after a couple of seconds. (Not Normal)
When key is turned to "start" position, displays for the radio and A/C control dim. Nothing else dims, volt guage does not move, and draw on system does not appear to increase. ( Not sure if the displays, radio and A/C, dimming is normal or not).
Turn key to "lock" and remove. Security light goes back to blinking. (Normal).
CCM code #53 set. (Pass Key Detection Circuit)
ECM code #46 set. (Pass Key Circuit).
Per FSM, code #53 troubleshooting, value of 255 obtained @ display 1.2 , lower reading of 06. (06255).
This, as best I can figure, is pointing to the lock cylinder wiring.
Guess I will get to the connectors on steering column and check.
I have not attempted to push start car. With all the above indications, I would assume the injectors are shut down?
I had been thinking about what to do to the car next. Guess I found it!!
Any more detailed information about bypassing the VATS if I need to go that way for a while? Marc mentions about jumping a switch, but have not seen any detailed instructions.
Please everyone, continue to throw me ideas. I will keep everyone posted on progress.