This started yesterday (when I let my wife drive the truck to school - coincidence I'm sure ). The truck will stop charging and the compressor won't engage. While driving, it will begin charging again every few minutes, then stop with no apparent pattern. I'm not getting a check engine light, nor a gen light when this happens.

I did some reading, and it seems the engine speed sensor could cause this. Is it beginning to fail, or are there connections I should check? Any other ideas?

 

Check the air gap on the crank position sensor. The gap should be .050".

 

Classic crank sensor symptoms. It's usually the wiring harness chafed though on the head, or the sensor is flopping around loose and bouncing off the damper now and then.

 

Thanks for the replies. I followed the wires from the sensor all the way back to where it goes into the large harness connector near the firewall. It looks to be in good shape with no corrosion in the connectors. The damper is also not loose.

Today I tested cruise and it worked. Wouldn't that also be disabled by the crank sensor?

 

yes I wager it is a bad sensor

 

Check the gap, it should be 0.050". A little tighter, say 0.040" will sometimes get it working. Use a non-ferrous feeler gauge.

 

If the sensor gaps out correctly, put some plastic wire loom around the crank sensor wire where it comes up and over the front of the engine. Mine was bad and it took forever to find the spot.

 

Does anyone know where to buy a non-ferrous feeler set short of ordering online?

It looks like the previous owner wrapped the whole wire in loom all the way from the sensor to the harness.

 

O'reily Auto has them, probably most of the parts stores do. Let your fingers do the walking.

http://shop.oreillyauto.com/ProductL...?Category=3393

 

A matchbook cover folded over once is close enough.

 

Well it turned out the gap was too tight. I took off the fan pully for easier access (those two bolts behind the pully are a pita) and adjusted it. Still no go. I'm just about ready to say the sensor is shot.

Can anyone send me the wiring diagrams, or tell me what pins on the ECU the sensor connects to? I want to test continuity accross the entire circuit. Thanks.

 

What about the relay on the fender? (can't remember what it's called) If it's sticking and the voltage isn't coming out of the ECM the compressor clutch is going to kick out due to lack of voltage.

 

That was my first thought when I realized the AC wasn't kicking in, but since the truck is also not charging, and cruise isn't working at the same time, I'm confident it's the crank sensor.