Dreaded No Start fixed (hopefully...)

[Locobob]

Also, where is the purple starter wire under the hood? I know it comes off the starter and goes into a smaller bundle but not sure where it goes from there. Don't really want to pull the plenum again to find it. Got any pics of the purple wire coming out of the harness?

[tccrab]

Originally Posted by Locobob

Also, where is the purple starter wire under the hood? I know it comes off the starter and goes into a smaller bundle but not sure where it goes from there. Don't really want to pull the plenum again to find it. Got any pics of the purple wire coming out of the harness?

LocoBob:
SpongeBob's cousin?

My digital cameras battery is dead, so can't get you a pic right now. Later today I'll get it charged and take a pic.

The purple wire is easy to find, remove the wire cover off of the ECM, it's held on by velcro, no bolts to take off. This exposes the main bundle going toward the motor. Open up the main bundle, you may have to cut some tape to open up the plastic sheath. There is only one #10 purple wire in the bunch.

It goes directly to the starter solenoid, but where it goes back into the car is anybody's guess. There's not a lot of room and there's a LOT of wires there.

TomC
'90ZR1 #792

[WB9MCW]

KUDOS TO YOU MR TC! THIS IS JUST THE TYPE OF EXCELLENT MOD/FINDINGS AND SOLUTION THAT HELPS THIS FORUM BE THE ONE WHERE THE TOP ZRONERS HANG OUT!!! EVENTUALLY ALL THESE GOOD TYPE OF POSTS ON SPECIAL PROBLEMS IN THIS SECTION WILL COMPLIMENT THE SECTIONS IN THE MAIN PAGE SITE! NOW IF WE CAN GET ZF TO FIGURE A WAY TO LIST AND CATALOG THEM FOR POSTERITY! LOL

[Locobob]

Found the big purple wire, it was buried pretty deeply in the big loom. You don't happen to have the part number of the Bosch relay handy do you?

[tccrab]

Originally Posted by Locobob

Found the big purple wire, it was buried pretty deeply in the big loom. You don't happen to have the part number of the Bosch relay handy do you?

I got the relay from my neighbor who's a diesel mechanic.
It's a common part, available from any decent parts store, Napa, Kragen, Autozone and the like.
It's exactly like this one:
http://www.partsexpress.com/pe/pshow...=330-070&DID=7

It's a 30/40A 5 pole SPDT (single pole dual throw) relay, made by quite a few different manufacturers.

Just go down to the parts store and ask for a 30/40 amp SPDT 5 pole relay.

Good luck!

TomC

[zr1mom]

From Marc Haibeck:

Here are some ideas on how to sort through an intermittent no crank
problem. This applies only to '90 - '92 ZR-1's. The wiring was improved in '93.
In the shop, the current on the purple wire to the starter can be
used to analyze the problem. The normal starting current on this
circuit is 10 to 12 amps. If the current is higher, there is a short
in the starter solenoid. This is a common failure mode. Often the
starter current will be normal when the engine is cold and too high
when the engine is hot.
If the no crank occurs on only about one out of a hundred starts,
another strategy might be better. Fabricate a jumper wire, 12" long,
14 gage, with male and female 1/4" spade connectors on each end. Plug
one end into the purple wire to the starter on the clutch switch
connector. Remove the aluminum crash panel from under the steering
column. It's attached with four 10 mm head fasteners. Remove the VATS
interlock relay. It's the relay closest to the left side of the car.
There are three yellow 10 gage wires on the relay socket. Plug the
other end of the jumper wire into one of the yellow 10 gage wires in
the relay socket. Crank the engine. Only one of the yellow wire
connections will work. If the engine does not crank try another one.
With this connection, the clutch switch and the VATS interlock relay
are removed from the circuit. The jumper connects the ignition switch
contacts directly to the purple wire going to the starter solenoid.
If the car doesn't crank in this configuration, the starter is the
prime suspect. The VATS, the interlock relay contacts and the clutch
switch are out of the picture.

[tccrab]

ZR1Mom:

This info needs to be on the Troubleshooting page of the website.
I actually figured out some of it myself when trying to diagnose my starting problem. I'd checked the Starter relay and the clutch safety switch. Didn't figure it was a VATS issue, no Security light and also the fuel pumps were working.
Anyway, this info needs to be saved for posterity.



TomC
'90ZR1 #792

[Locobob]

Rewired mine several months ago = no more starting problems! One thing I'd like to add - It's a good idea to put a fuse on the new battery to starter wire, put a 15amp on mine just off the power dist. block where I sourced my battery power from.