Another Intermittent No Start Thread

Please help me understand your chart a little more. Are you saying that you've had two completely different solenoid/starters on the car, and both will not engage even though the voltage on the "white wire" is 11.85V in each case? I.e., during the no start (no nothing?) event, the voltage on the white wire (at the solenoid) is 11.85V, when the key is in pos III, but neither solenoid never engages?

 

Have to say that that almost exonerates either solenoid/starter, but are you saying that you actually measured 11.85V on the white wire during "no start" events (key in Pos III) when using both starters?

 

Do I understand that you have 12.35 volts at the battery and 11.85 at the starter? If so, that is a dramatic voltage drop and indicates either faulty cables or poor connections.

 

Do you have the white wire connected to the solenoid terminal 50 when you are making this voltage measurement? (you should)

Also, if you can touch the ground probe of the voltmeter to the starter motor casting/flange that would give the best indication of the actual voltage across the solenoid winding (if you are touching the ground probe somewhere else).

 

Anything more than around 3% voltage drop is a problem for hi-draw circuits. The voltage drop test is the most effective way to test a circuit for whatever its intended purpose. That much of a drop indicates a problem. It could be a bad battery as well as wiring/connections.

11.85 volts is very low voltage to spin a starter motor. In fact, many electronic ignitions/fuel injections will not function at all at that low a voltage.

Battery cables can be bad internally and look fine externally. The standard thing anytime electrical systems are being looked at is "check the grounds."

 

Understood, but without being connected (i.e. under load), the 11.85V is really a meaningless value (because the current in that case is 0 amps, so a bad connection upstream doesn't have much adverse effect on the measured voltage). I'll make a wager that the real voltage on the white wire (when it's connected and you have the "no start" problem) is much, much lower (and you have a bad, but not totally open, connection in the white wire somewhere between the ignition switch and the solenoid).

 

Probably OK - basic things, like the starting system, are usually the same for all versions. The good news is, if the voltage on the white wire at the solenoid is low, the next place upstream to check is at the C4 connector in the engine compartment.

You might need to fabricate a short male-to-female jumper wire, with another (longer) wire attached, that you can connect inbetween the existing white wire end and the terminal 50 male tab on your starter -- that way you can run the additional long wire temporarily into the passenger cabin (thru a window) so you can monitor the voltage during start attempts more easily.

 

Wade, I had an intermittant start problem on my '88 mondi cab too, with exactly the same symptoms you describe. After hunting around at the various possibilities it turned out to be a poor connection at the fuse box. Does one of the white (multi-wire) plugins at your fuse box (believe it's lower right when viewed from the drivers seat perspective) have any burn marks (brown or black) in the area of the contacts? I cleaned and re-soldered mine there and that fixed the intermittant start problem.

Good luck!

 

I troubleshoot such issues by bringing another battery and wire set under the car. By using a fabricated ~2 ft starter-battery wire (plus solenoid wire w/pb switch). And use a ground wire with jumper wire type clamp, so one can put the ground on the frame and also on the starter to prove out ground issues as well.

Starter problems always seem unique and this method eliminates half the car. Divide and conquer.

 

I've had to replace the actual swith part of the ignition switch. I've learned it to be a fairly common problem. The price varies greatly. Maybe somebody will mention a good source. I bought mine 20+ years ago from the dealer and it wasn't to bad. Something to check anyway.

 

From your visual description, it seems these red wire connections at the w connector are OK, but, again, this voltage needs to be measured when the key is in pos III (and did you have the engine running? -- the no-load voltage of a lead-acid battery should be 12.6V max, and might droop down to ~10V during actual starter motor cranking). You've got the voltage measurement on one side of C4 (showing the trouble is still upstream from there), but, it just becomes a case of measuring the voltage when the key is in pos III until you find the transition from OK to not OK in the path from the red wires in the w connector -to- ignition switch terminal 30 -to- ignition switch terminal 50 -to- connector C1 -to- connector C4 -to- (you've already check here)...

Did you unplug/inspect/reseat the C4 connector connection or make the same measurement on the uptream side of the C4 connector? (Seems like a place that could be exposed to the elements).

Good Hunting!

edit (after seeing your latest post):

Welcome to one of the problems in chasing an intermittent Gremlin -- just getting in to make a measurement can disturb things enough to make a bad connection into a good connection. I'd definitely, unplug/inspect/clean/repair-as-necessary that unnamed connector, but, unless your starting behavior acts up again, it can't be fixed or even investigated

 

I spent the better part of last summer chasing this on two Mondials, one T Coupe and one 3.2 QV.... two of the most patient Mondial owners on the planet who tolerated test lights hanging under the dash, jumper wires in the trunk.....

Remove and polish clean all the connectors at the positive battery cable end accessory terminal and solder all of the crimp terminals to the wires... re attach and secure. Photo the red supply wires where they enter the fuse box and post it. (3.2 QV)

Remove the plastic plug at the end of the ignition switch harness, solder and shrink tube all of the wires to the car harness, eliminating the plastic plug and the resistance through the spade terminals (T Coupe)

 

Wade, looks like you're in good shape there. Just thought I'd mention the possibility. Those two wires were somewhat corroded in my plug with some signs of browning and it was causing intermittant start probs.

You'll get it nailed down - good luck and persist!