About two weeks ago I had to jump start my 92 Dakota and sparked the battery by touching the terminals to the wrong post but the ignition was turned off and when I tried to start it the truck ran fine. I drove the truck a couple times but the next time I tried to start it it started and turned off right away and wont start again. I was told the most likely problem was the crankshaft position sensor so I replaced it and it still won't start.
I then looked in my Chrysler corporation manual and checked for spark and there is no spark, then I checked voltage to the coil and it is between 5-6V while cranking the truck for 5 seconds.
My next test was the crank position sensor and the book says that with the tab facing up that the two prongs on the right "the meter reading should be open ( no resistance). Replace sensor if resistance is indicated." From what I have read on the internet open would mean infinite resistance, Not no resistance, but when I tested the old sensor it read infinite and the new sensor read infinite as well as 3 new ones at the store so I am confused as to whether I should have no resistance as in (touching the probes together 000) or if it should read infinite as in an open air gap between the probes. Does anyone know which reading I should be getting? The reading I get is the same as having a gap between the probes. If this is the correct reading (which the book sounds like the opposite is true) then what should I check next?

I have bought several bad parts in a row before so I wouldn't rule out a bad batch of sensors at the auto part store or the dealership but I would like to know that the cps is actually working before trying to troubleshoot other parts.

I appreciate any help, I could sure use a truck that runs.

just figured out I posted this in the wrong place but I can't figure out how to move it.

 

I will move this to the 1st generation Dakota sub-forum.

 

When you turn the key forward and all the lights come on, does the check engine light come on? Also have you checked the wiring near the fuse box? Not sure if your year has the notorious wire problem... Mine had a corroded wire and when the PCM wasn't working, the check engine light would not light up.

 

To reply about resistance... If a switch is open and contacts are not touching, you will get no reading which is a infinite resistance from what I remember from school. When you touch your probes, the meter reads the resistance in the probes and 00 means its calibrated. When you touch the prong with open contacts, it should read the same as if you were not touching anything with the probes if that makes sense.

 

I see you were advised to replace the Crankshaft position sensor. This could possibly cause and clear your fault because a bad crankshaft position sensor shares the same 8 Volt supply from the PCM as the Camshaft position sensor. A bad crankshaft position sensor may drag down the signal from the camshaft position sensor. Both sensors are located behind the throttle body. The crank sensor is located on the passenger side where the block meets the bell housing, near the EGR valve assembly. The camshaft sensor is found in the distributor, under the rotor. It is the signal from the camshaft position sensor, not the crankshaft sensor, which the PCM monitors to determine whether to continue to furnish ground to the ASD and fuel pump relays. No signal is interpreted as a non-running engine, consequently, ignition and fuel are terminated two seconds after the key is turned to "Start" and you're left with a dead engine. If a code is stored, it should be an 11 or a 54. Do you know how to retrieve codes with the key on-off-on-off-on? At the third "on", observe the check engine lamp for flashes. A 1-2 is a twelve, means the battery was disconnected since the last 50 starts. A 5-5 means the PCM has finished its report, you'll always see this. If you get a "55", with or without other codes, you'll at least know you have not fried the PCM (computer).

The camshaft position sensor (aka; distributor pick-up) is a Hall effect device. Put simply, all bipolar transistors "turn on" (conduct) to a greater or lesser degree, as a magnetic field sweeps through the base of the transistor. The field moves electrons, this constitutes a current in the base, which is what's needed to induce conduction from the collector to the emitter of a bipolar transistor. A bipolar transistor is one which has a base, collector and emitter. The base is the control, the collector and emitter may be thought of as the poles of a switch. The maximum current from C to E is some multiple of the base current. The "multiple" is referred to as the Hfe or "beta" and characterizes the performance of our hypothetical transistor as an amplifier.

Hall effect transistors are constructed to maximize the magnetic effect. So far, so good, but now I'm gonna go out on a limb.
You can induce your sensor to go from open (infinite resistance) to closed (conducting) by passing a strong magnet quickly over the sensor. If the meter is quick enough or is sophisticated enough to have an auto hold feature, you may visualize the transition. It will, however, be very short. The sensor requires a voltage source on pin 1 of about 8 Volts, ground on pin 2 and the signal should appear on pin 3. Looking at the sensor connector with the indexing tab on the bottom, pin 1 is on the right and pin 3 is on the left (according to the Factory Service Manual). An oscilloscope would be ideal for this trick, since you can then manipulate the time base. If you get around to giving this a try, be sure to post the result.

 

Yes, I talked to my brother who is an airline mechanic and he explained the difference between an open and closed circuit on the ohm meter. I originally thought that the book was incorrect because it said that "it should read open ( no resistance) replace part if resistance is indicated" I thought that open meant infinite resistance but they said if there is resistance indicated that it was bad and that didn't make sense to me. He explained that if the two leads of the ohm meter were not touching that that is open and if I touch them that the 000 indicates some resistance so when I touched the prongs of the sensor the meter should read the same as when the leads are not touching and if it changes that means there is resistance which would indicate a bad part. I finally decided that the CPS is not bad.

 

So far we replaced the crank position sensor and cam sensor and nothing changed. I checked for codes ( the check engine light was not on) and the only code I got was for the AC relay which was not installed. I checked for continuity from the auto shut down relay, also from the 60 way connector to the negative on the coil plug as well as the 3 grounds from the truck body to the 60 way connector and they all tested good.
While the truck is cranking the auto shut down gives power to the coil the whole time so I don't think it would be the cam sensor and if I ground the coil off the engine block I recieve 11V (with a weak ground). I think I said before that I can get a very weak spark with only 5-6 volts going to the coil if it is connected to the CPM. My understanding is that the auto shutdown relay provides power to the coil and the CPM provides the ground so since I tested the grounds to the CPM and the voltage from the auto shutdown relay I figured the only reason for not having a strong enough ground was probably the CPM so I replaced it and nothing happened.
NOTE: the CPM came from auto zone with no protection over the prongs or warnings about not touching them so they may have been shorted out already.
I talked to my brother the airline mechanic and the first thing he said was try another computer so we may try this but I am not too hopeful at this point, although with our ford f150 we had a mechanic replace the CPM and the truck ran horribly so he wanted to spend hours checking the wiring harness but we couldn't afford that so we searched for a used harness and could not find one and then decided to check the old one ourselves. It all tested good so we replaced the CPM ourselves and the truck ran great so we have bought bad computers before as well.
any other thoughts besides the computer, crank and cam sensors and auto shutdown relay would be appreciated.

 

If you have part of the battery voltage showing up at the coil for as long as you crank, this indicates to me that the PCM 'sees' the camshaft signal and is attempting to furnish ground to the coil. I would next suspect the chassis connection that provides ground to the PCM. In '93, pins 11 and 12 were power ground.
Looking at the PCM connector from the PCM side (as opposed to the wire side) 11 and 12 would be on the right side, top, with 11 closest to the middle of the connector. Check for less than 5 Ohms from both pins to a solid chassis ground. Be very careful not to damage the connector in any way while probing it, a thin paper clip may prove to be a good fit. The physical location of the ground is given as the left headlamp ground on the left fender shield.
How 'bout the fuel pump? Do you hear it running while all this cranking is going on? Have you checked the fuel pressure? It should be in the range of 31-32 psi.