Our '85 coupe just started acting up yesterday. When I went to start it, all the starter solenoid would do is click. Figuring the solenoid was shot, I replaced the starter with a known good one I had on my shelf, but still had the same issue. This car has been starting great for the last year up until yesterday. So I start troubleshooting, and with the ignition switch in the start position, I'm only getting between 8-9 volts at the switch pole of the solenoid. From the two wires on the switch pole back to the C500, I have no resistance. So I probed the red wire that comes into the C500 from the firewall, and I'm only getting between 8-9 volts before the C500. I went inside, disconnected the clutch safety switch, and I am getting 11.5V when the ignition switch is in the start position.

EDIT: New question, please see below

[This message has been edited by Hulki U. My-BFF (edited 06-28-2011).]

Yes - one continuous wire from the clutch switch to C500. It routes across the dash to the middle console, then back through the passengers side firewall bulkhead fitting, across behind the battery to C500.

quote Originally posted by phonedawgz: Yes - one continuous wire from the clutch switch to C500. It routes across the dash to the middle console, then back through the passengers side firewall bulkhead fitting, across behind the battery to C500.

Thank you very much phonedawgz, I kind of figured but was not sure.

Well, I'm officially stumped. I went out tonight to test the car further. At the yellow wire from the ignition switch to the clutch safety switch I had 11.7V. But any time the circuit was completed, the voltage would drop to 9V. I then probed the purple wire the entire length from the clutch safety to the starter solenoid, with no resistance in the wire. Stumped, I ran a jumper wire from the switch pole of the starter solenoid directly to the battery. The car turned over and started. So that told me that the solenoid was good. But then, I took the jumper wire off, tried to start the car normally, and whammo! It started. I shut it off and started it again, and again, and again. I have NO idea what happened, but it is starting for the time being. Any ideas?

Also, when I was testing the car before it started, I jumped the yellow and purple wires with a wire of the same gauge, and the voltage still dropped to 9V. So I know the clutch safety switch was not the issue.

Checking for the voltage requires a load connected for you to find the problem. So make sure the starter solenoid is connected. It would be good to have the battery fully charged also if it is not.

Then try measuring the voltage on the yellow wire at the clutch switch with everything connected. Low voltage at the yellow wire? Then measure the voltage on the red wire of the ignition switch when you turn the key to start with everything connected.

The path of the starter

Battery - Power Distribution posts - fusible link - fat red wire to the ignition switch - yellow wire from the switch to the neutral switch - fat purple wire to the starter.

Checking the voltage when the key is turned to start with the starter connected should give you a clear indication of where the voltage drop is.

My guess is that it is the ignition switch BUT that is just a GUESS.

Measuring the voltage will tell you where the problem REALLY is.

Thanks for the reply, phonedawgz. I should have mentioned, I tested with the clutch safety switch disconnected, and tested with the complete circuit connected. Holding the start switch on, the solenoid would click once and the voltage at the safety switch and the solenoid was 9V.

[This message has been edited by Hulki U. My-BFF (edited 06-28-2011).]

So you do have the full +12v at the battery when you preform the test?

Or are you just looking at a low battery that drops to +9 during cranking.

quote Originally posted by phonedawgz: So you do have the full +12v at the battery when you preform the test? Or are you just looking at a low battery that drops to +9 during cranking.

It's 11.6V at the battery, albeit a little low, it recovers without hesitation after the key is released from the start position. Thinking the battery was a possibility, I put my battery charger on it and used the starting booster function of it. Still the starter would only click once loudly.

So you drop 3v by the time of the clutch switch. It would be good to check on both sides of the ignition switch to see the actual drop across the switch.

quote Originally posted by phonedawgz: So you drop 3v by the time of the clutch switch. It would be good to check on both sides of the ignition switch to see the actual drop across the switch.

I'll check that out and report back. Thanks, man!

Had the battery load tested yet? Are the cable ends corroded?