I have an 85 4+3 z-51.

The problem is intermittent. It happens after many successful starts. For example.
Scenario 1:
I stall the engine by mistake (too low rpm when starting to drive). When I shall restart the starter is dead. The dash lights are normal and do not get darker due to current consumption of starter. I can try and retry but the starter is dead. By accident i discovered that loosening the negative battery cable bolt slightly and retorqe it solved the problem. Thought it was corrosion on the battery connectors. Rinsed them allthough they looked perfect. After some week this happened again.

Scenario 2:
I drive and then stop the car, go into a shop and come out again.Then the same symptom. This happens once in many incidents (starts).
Every time retorqing the battery neg. cable solve the problem.


The cables looks perfect and so do the connectors without sign of corrosion both the pos. and neg. cable. The starter behaves fine. What can it be????
There is no clicking in relays or solenoid. It seems that the solenoid does not get any current at all. Why should retorqing of the battery connector solve the problem as there is obviously enough voltage and the battery is new.
What disturbs me is that there are a connection to ground as the dash is illuminated and other electrical equipment get what they shall have of voltage and current.

I sincerely hope that somebody can help me out of this.

Jan-Erik

 

Probably the cable connections aren't related except that you reset the ECM or 6 minutes went by and VATS was reactivated. VATS (vehicle antitheft system) measures the resistance of the pellet on your ignition key and compares it to its memory and if the resistance exceeds 5% error it won't close the start enable relay and it tells the ECM to not pulse the injectors. If you try more than 2 times the ECM shuts down for 6 minutes and won't allow a start. In series with the start enable relay is the clutch safety switch (gear selector switch if automatic) and if defective, the starter solenoid gets no 12v when you hit crank position on the ign sw. Next time try jumping the clutch safety switch after one unsuccessful try to crank and then try again. There are contacts in the ign tumbler that make connection to the pellet and they wear. You can determine if this is causing your no start by removing the hush panel above the drivers feet and find the pair of wires from the steering column (white on my 87) that go to a 2 pin connector. Unplug the connector and with your ign key inserted, measure the resistance across the wires from the steering column. It must measure the same as the pellet. If over 13k ohms or different than the pellet, you need a new ignition tumbler. You can temporarily bypass VATS by clipping a 1/4 watt 5% resistor from Radio Shack the same value as your pellet onto the wires going into the harness until you can schedule a tumbler replacement. Don't permanently bypass your VATS because 99% of thefts are done by bashing the column and jumping the ignition.

 

85 doesn't have VATS....no resister in the key..........but do try by passing the clutch pedal micro switch

 

Hi.
Thanks for the answers. I will bring the VATS problem description to a friend who have an 86.
That is correct. I do not have the VATS function.
What is strange is that it seems not to be the clutch switch. Why? That is because I do try to restart some times before going out and retorque the battery cable. When restarting I also operate the clutch so that the switch is moved. To retorque the cable is 100% success. If there had been other influences wouldnt it be a chance that there would have been other symptoms or at least not a 100% success with retoqueing.
I have thought of a voltage drop From the ign. switch to the solenoid so that the solenoid would not have enough voltage and that this could be dependent of the heat. But it also happens when the heat is not very high as in the summer.
I am still a question mark because it seems not to be any logic here.
Jan-Erik

 

Hmmmm, Google led me to believe that 85 was the first year for VATS.
You clearly have a bad connection to the battery. Remove the battery cables (neg first) and clean the cable lugs and the battery posts and the bolts and replace (neg last). You want your battery connections to be like your lover, bright and tight!

 

The first thing I'd do is buy new battery cables. You probably need new ones anyway, it's a cheap fix, and they could be corroded inside the insulation.

 

 

just wondering if it could be a bad connection inside the battery itself.when this happens does the rest of the electical systems work?headlights come on,radio works?