Mechanics

DODGE CARAVAN SENSOR PROBLEM

1996 Dodge Caravan • 90,000 miles

Replaced power steering hose, drove it a block, died and won't restart. Cranks, no check engine light comes on, did get oil light at first, (all fluids are fine), get no problem codes, doesn't even get vin number or other car info from computer, there's no spark at all, I replaced crankshaft positional sensor, engine getting fuel, have all new spark plugs, battery good, gas tank half full, sprayed ether at carb: no cough, don't know what to do. I desperately need this car to run, any help appreciated! Thanks, Katie
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Kmcelhinny
January 26, 2013.



Which engine do you have? How do you know you have fuel? Are you referring to fuel pressure or fuel spraying from the injectors?

Was there a spacer on the end of the new crankshaft position sensor? Do you have a scanner that displays live data?

Caradiodoc
Jan 26, 2013.
I have a 3.3 v6 engine. The injectors are spraying fuel, we sprayed ether at the carburetor and didn't get a cough even. New battery tests fine, no spacer on the crankshaft position sensor, replaced the Ignition coil, our scanner does not display live data.

Tiny
Kmcelhinny
Jan 26, 2013.
The crank sensor's air gap is critical. New ones from the dealer have a thick paper spacer stuck on the end. Many aftermarket ones have a thin plastic rib molded to the end. If you reinstall a used one, you are to cut the remaining part of the rib off and use a new paper spacer.

A scanner will show the crankshaft position sensor and the camshaft position sensor as "no" or "present" during cranking. If either signal is missing, the Engine Computer won't turn on the automatic shutdown (ASD) relay. That relay sends current to the ignition coil pack, injectors, and fuel pump or pump relay. By far the most problems occur in the sensor circuits and you have no spark and no fuel. The pressure can be misleading because the ASD relay still turns on for one second when you turn on the ignition switch. That runs the pump for one second and gives the appearance of good fuel pressure.

If you removed the injectors and saw them spraying fuel during cranking, the ASD relay has to be turning on during cranking and there's no need to go looking for a sensor problem. Besides that sensor circuit, you only have the ignition and fuel systems. Both are responsible for relatively few problems but it sounds like spark is all that's missing. That leaves the coil pack and the wiring to it. I suppose the computer could be not firing the coils but it's rare for one circuit to fail and it would be even more unlikely for all three circuits to fail. I think I'd start by measuring the common 12 volt supply to the coil pack. If that is missing due to a broken wire or corroded connector pin, all three coils will be dead. That should be the dark green / orange wire. You can use a stretched out paper clip as a probe to go through the rubber weather pack seal next to the wire. You should see 12 volts on that wire for one second after turning on the ignition switch. If you do, the wire is okay. If you do have it for one second but it doesn't come back during cranking, you have a sensor problem, and the injectors can't work either because they're on that same circuit.

Caradiodoc
Jan 26, 2013.
There is a spacer on the end of the crank position sensor thick paper like spacer. So far there is no spark, with all new plugs. Injectors are working, saw them squirting fuel. Replaced coils so cant think why there is no spark. I have located the green/orange wire and I should just hit it with a voltmeter? And should the housing the wire is in be plugged in when testing or unplugged and try to crank it over to see if there in current going through it? Still just amazed it isnt working.

Tiny
Kmcelhinny
Feb 2, 2013.
You saw the injectors squirting fuel? Are they out of the engine?

To test for voltage at the coil pack use a stretched-out paper clip to slide through the rubber seal alongside the dark green / orange wire. You should find 12 volts there for one second after turning on the ignition switch. If you do not, assume it's not making good contact with the terminals, and move the paper clip around a little. You can also unplug the connector and measure right on the terminal, but a test light will give more accurate results than a digital voltmeter.

If you see that voltage for one second, see if it comes back during cranking. If it does not, the injectors can't be working because they are fed from the same circuit. If the voltage does come back during cranking, but the coils aren't firing, there's a problem with the Engine Computer. That would not be common.

Caradiodoc
Feb 2, 2013.