No crank condition - need suggestions

[KFoster]

I haven't found this issue, but I bet someone has covered it. 1990 ZR1 will not crank at times. Did it a few times this summer and I thought it was temp related as it cranked fine cold, but then it would not engage starter. No cranking, but all electrics worked fine. Leave it to cool over and it would fire right up. Now, it does it cold. Leave it alone for a few hours and it will crank right up. Maybe a sticking relay? Clutch switch? Any ideas? In my experience, relays won't just unstick. You can tap on them and get them to work, but in this case I did not do that. Did nothing more than leave it alone and try it later. Now I'm afraid to turn it off anywhere but home. Help.

[RussMcB]

I think the first step would be to prepare for bypassing a lot of things the next time it happens, so you can send 12v directly to the starter from the battery. That will tell you if it is starter-related or not.

To prepare, you need to locate the "purple wire" that goes from the ECU (correction - UNDER the ECU) to the starter. Make some kind of jumper connection so you can connect 12v to that wire. You will, of course, need to make sure the car is out of gear.

If the starter works with your jumper wire, then you can start debugging the other possibilities, such as VATS, clutch switch, etc. If the jumper doesn't solve the problem then you'll need to remove the plenum and troubleshoot in the starter area.

If you do a search for Purple Wire in this forum you will get plenty of details and pictures.

Oh, and park on hills. :-)

Off topic: Can we see a pic of your Pantera?

[KFoster]

Hopefully this will show up.

[RussMcB]

Nice! I like how you two dressed to match the car. :-)

[We Gone]

http://www.zr1.net/forum/showthread.php?t=21388

Check the sticky at the top of the page lots of great info.

http://www.zr1.net/forum/showthread.php?t=16778

[RICHARD TILL]

The contacts in the solenoid would also be a likely suspect. Fixed mine twice with the same problem. Cheap fix. I`m about 75 miles east of you. Shout if you need any help.

[KFoster]

Richard, I appreciate it. I didn't think about the solenoid. Never had one act like that, but could be. I will try to bypass the clutch switch when it does it again and then check the solenoid. Good ideas from everyone.

[Dynomite]

Exactly as Richard, Steve, and Russ suggest.....but messing with the Starter requires a bit of surgery requiring you put the car to sleep (that is my euphemism for removing some coolant) which is required unless......unless....you block TB Coolant

Starter, Starter Relay, Wiring Harness, Battery, and Plugs Tricks

Electrical Ground Connections and Installing Starter Relay

See this link for TB Coolant Blocking drilling and threading details Injector Housing TB Coolant Blocking

I have blocked TB Coolant in an LT5 without removing the Injector Housings (recommend removing the two Injector Housing Coolant Manifolds however).

[Paul Workman]

Originally Posted by KFoster

Richard, I appreciate it. I didn't think about the solenoid. Never had one act like that, but could be. I will try to bypass the clutch switch when it does it again and then check the solenoid. Good ideas from everyone.

Marc Haibeck presented these procedures at the Bowling Green spring gathering, one or a couple years ago. This and much more info is also on his site. For you reading pleasure...

[Z51JEFF]

THE PURPLE STARTER WIRE DOES NOT COME FROM THE ECM. The wire runs UNDER the ECM. Misinformation will only add to the confusion here folks.