'94 Merc Sable 3.0L No Start, No Crank condition

[Clement]

'94 Merc Sable (130K miles), won't start, won't crank. The owner replaced the starter and ignition relay (I think, it was in the steering colum), still no start.

If the key is turned to start, and the starter motor is jumped, the engine will start and run fine. The battery has been replaced.

I know, this guy has been throwing parts at it. I sold him the car, so I figured I'd ask the experts here for a little advice. From what I've been able to figure out, this could be a grounding issue, or the control module above the radiator. Yes/No? Is there a way to check the control module with a meter?

One more point, for a while, this was an intermittant problem, which seemed to clear up after fiddling with the battery cables. However we've checked the voltage off of the cables and the grounds next to the battery. Should we be checking resistance instead?

Thanks for your help.

 

[brianl703]

Ignition switch, maybe? Check that the starter relay gets power (on the thin wire attached to it) when the key is turned to the START position. If so, it's not a problem with the ignition switch.

The control module has nothing to do with it. That is just the ignition module. If it cranked with no start it would be suspect.

Checking voltage without a load tells you NOTHING about the condition of the cable.

You need to check the voltage while you are cranking the engine. If it drops way down while you are trying to crank the engine but then goes back up when you stop, the problem is between there and the battery.

The starter circuit on this car is not very complex so it shouldn't be difficult to find the problem.

 

[punisher]

From what you describe, I would suspect a neutral safety switch/MLP sensor. When starting problems occur, shift the car into neutral and try to start it again. If it starts OK in neutral, then you found the problem. Switch is on top of the transaxle where the shift cable hooks into it. Sometimes the switch will get loose and move causing a problem. Put the car in neutral and ck the alignment marks on the switch, if they line up, the switch is positioned correctly.

There is no relay that controls the starter in the IRCM mounted on the radiator support to my knowledge.

If you jump the starter solenoid and it turns over, you know the cables, power and ground are good, that leaves the wire to the solenoid as the problem child. Power to that circuit is governed by the ignition switch and the neutral safety switch.

If you have any more questions I have the Alldata info for that year.

 

[brianl703]

You can download the manual here:

http://www.fordcds.com/

 

[Clement]

Thanks!
I had already tried to start the car in neutral, didn't work. I passed the info on, I'll let you know what the conclusion is.