My '95 Dakota started fine, then sat for a month, and now it will not start. It cranks fine, and smells like it's getting fuel, so I've ruled those out.

I haven't been able to get a spark off the coil when cranking the truck, but I removed the coil and tested it, and was able to produce a spark on the workbench.

I followed the guide for testing the ASD Relay socket, and it seems ok, but when the key is in the start position, terminal 85 only drops to 7 or 8V, never to ground. Is that a normal reading for when the relay is removed?

I have the manual on how to test the camshaft position sensor, but I can't figure out a way to get access to the wires. I may just replace it if a new one is cheap.


Any other suggestions on what I should try?

Thanks

 

If it -is- getting fuel, the ASD should be good (it feeds the coil, and all the fuel injectors.)

You might try removing the distributor cap and seeing if the rotor inside spins when cranking the engine.

Besides the camshaft sensor (under the distributor cap), a bad crankshaft position sensor (located in the engine compartment, on the passenger side, where the engine and transmission mate up) could cause problems as well.

Simple things first.

 

Just for fun, I shorted the output contacts of the ASR relay so that it would always be on. Still no spark. I need to get to the wiring to check the two sensors still, so that's next on the list. If they check out, what are the chances the ECM has gone bad? Is that a common problem?

 

While anything is possible, computers are actually fairly reliable. Granted, anything that is 17 years old, in the automotive world, is old, and can be prone to failure.
I would not jump to thinking it is the computer.

 

I get little 15 minute bursts of time to work on this. The last thing I checked was if the coil was getting 12V with the ASD relay removed and the output of the ASD relay shorted to the input. - It was. I then put the ASD relay back in and checked to see if the coil got 12V when the key was moved to start - it did not. My next step is to check continuity on the wire that connects to the coil of the ASD relay, since I know the relay itself is good, but for some reason it is not engaging. If I have continuity on this wire, what could the problem be?

 

According to the wiring diagram, for the 1995:
Terminal 30 of the ASD comes from the battery (obviously, since that needs to be hot at all times)
Terminal 87 is the "energized" output (for the coil, oxygen sensors, fuel injectors, etc)
Terminal 86 is the "switched" input, which comes from the ignition switch. (Positive voltage in the START and RUN positions)
Terminal 85 is where the ground comes from. The interesting thing about 1995 and previous years (versus 1996) is the fact that the ground provided to terminal 85 from the computer is SHARED with the fuel pump relay.

So, given that, I would check to make sure that your switched positive (terminal 86) from the ignition switch is good.
If you are, in fact, getting fuel (if you even hear the fuel pump turn on), your ground should be good for the ASD, since they share that ground from the PCM.

If the power from the ignition switch checks good... it would look like either the relay is bad, or you need to dig somewhere else. (Not the computer)

As I said earlier, also try removing the distributor cap, and see if the rotor inside spins. (I had a similar issue [no spark, no voltage], I eventually checked, and distributor wasn't spinning - I had a broken timing chain)

 

According to the wiring diagram, for the 1995:
Terminal 30 of the ASD comes from the battery (obviously, since that needs to be hot at all times)
Check

Terminal 87 is the "energized" output (for the coil, oxygen sensors, fuel injectors, etc)
No voltage present here when starting.

Terminal 86 is the "switched" input, which comes from the ignition switch. (Positive voltage in the START and RUN positions)
Terminal 85 is where the ground comes from. The interesting thing about 1995 and previous years (versus 1996) is the fact that the ground provided to terminal 85 from the computer is SHARED with the fuel pump relay.
Going to try and listen to fuel pump now, but I suspect it isn't functioning either.

So, given that, I would check to make sure that your switched positive (terminal 86) from the ignition switch is good.
Check

If you are, in fact, getting fuel (if you even hear the fuel pump turn on), your ground should be good for the ASD, since they share that ground from the PCM.
Ground appears to be bad (see below)

If the power from the ignition switch checks good... it would look like either the relay is bad, or you need to dig somewhere else. (Not the computer)
Relay checks out as good. I removed the huge header from the computer and tested continuity to terminal 85 of the relay. It tested out good, but for some reason the computer is not switching ground to energize the relay. Directly connecting this terminal to ground produces an audible click from the relay and output voltage on terminal 87.

As I said earlier, also try removing the distributor cap, and see if the rotor inside spins. (I had a similar issue [no spark, no voltage], I eventually checked, and distributor wasn't spinning - I had a broken timing chain)
I checked and the rotor does spin.