I have a 1999 expi that has become troublesome. It will not turn over, or crank if you will. I believe it is the solenoid, but when I was checking voltage to it I was seeing something that did not make sense to me. With the ignition off I read 4 volts. If I shift it out of park or neutral then it reads 0 volts. When I turn the ignition to start while in P or N then I get 12 volts, and 0 if in another gear as expected. This tells me the neutral safety switch is working.

What I am not sure about is why I am getting 4 volts with the key off.

 

You have to tell us WHERE the meter leads are connected.

 

Sorry, I was checking the voltage to the S wire, the one that comes from the ignition to tell the solenoid to fire.

 

By the "S" wire, are you refering to the tan wire (that comes from the DTR sensor) that pulls in the starter motor RELAY up on the firewall?

Or are you refering to the red wire (that comes from the starter motor relay) that is connected to the "S" terminal on the starter motor SOLENOID down on the starter motor?

And is the wire connected or disconnected when you take your meter readings?

And what postion is the ignition switch in when you are taking each reading?

 

Specifically, where are BOTH meter leads connected.....

 

There are three wires on the relay/solenoid on the firewall. I am checking the small gauge wire with my positive lead of my Fluke. The negative lead is on the negative battery post.

 

Pull fuse F20 in the under dash fuse box. If the 4 volts goes away, it's just some leakage voltage coming from one of the other assemblies that feed off F20 (Radio, GEM, Driver's seat module, air suspension, etc) and is just a curiosity, not related to your 'no crank' situation.

 

What projectSHO89 said, but if you are seeing some voltage (with fuse #20 AND #21 pulled) on that tan wire while it is connected to the relay a bad relay may be leaking voltage into the relay's coil.

 

If the solenoid on the starter has in any way leaked water into it, you're getting voltage internally leaking from the +12 volt battery lead through the water to the S terminal.

 

Don't think so since he said, that when the shifter is moved out of the P or N position, the measured voltage drops to zero.

In any event, it's a curiosity unrelated to his actual starting problem.