I have no signal from the ECU to my ignition coil. I have good fuel pressure and the injectors are firing as the engine turns over so I know the ECU is receiving a signal from the hall effect sensor in the distributor. When it first died I was able to give the ECU a good smack and it started back up and ran good for a few days, until tonight when it died again and smacking the ECU no longer works LMAO.

Before I dish out the money for a new ECU is there anything else I should check? I though about running a new wire from the ECU to the ignition coil but I have traced the wire and do not see any obvious damage to it so that may be a waste of time.

I followed a tutorial on checking the hall effect sensor and I have the 8VDC going to it and I see 5VDC as I turn the engine over. I also put a voltage light on the negative side of the ignition coil and it lights up when the key is turned to the on position but it goes out and does not blink when cranking the engine.

 

Check engine light working? (Comes on with ignition then goes out) Any codes? May want to remove the connector from the ECU and inspect for any issues.

 

You really need to use a NOID light; the ON will be short enough, especially an incandescent won't light up to where you can see it on the ECU side of the coil.

I'd check continuity to the coil.

Besides, the light should go ON and turn OFF while the coil is running. The 12V into the coil will be there the whole time the engine is turning over or during the ASD prime cycle.

RwP

 

The check engine light is working. I have error codes 12 - Power loss to ECU, 41 - Generator not switching properly and 55 - end of error codes.

I assume error code 12 is because I disconnected the plug to the ECU and error code 41 is because the voltage regulator built into the ECU went bad a couple years ago and I wired an external voltage regulator to it instead of replacing the ECU.

I bought a new ignition coil today just to try it out and it did not fix the issue. I checked continuity on the wire from the ECU to the coil and it Ohmed out good so I guess I will just order a new ECU, sucks that shipping is 7 to 10 days!

Are there any other ECUs from other years that would be compatible or maybe other Dodge vehicles?

 

Ralph would be the expert on that, all I can tell you is that car-part says 91 5.2 Federal emissions is by itself for PCM, but why I can't say. Personally I'd try any 5.2 before 96 to see if it would run. Car-part says there's one at First Choice Auto Salvage in Coopersberg PA for $50, that's as cheap as I've seen. It also doesn't seem to matter if it's AT or MT nor does it matter if it's 4x2 or 4x4.

There's a couple V8 Dakota's where I am but not 1991, and I would have no way to test the PCM to be sure if it was good before sending it on. I think you're best bet is either reman or the one in Coopersberg, or check with Hollander website too.

Steve

 

Well, the 91 is TBI; 92 up is MPEFI, so the ECU's won't swap.

A 1990 MIGHT work; but might not.

I'd stick with a 1991 myself; there are a few listed at car-part.com .

So you're positive you're getting 12V to the coil while cranking? I'd check continuity from the ASD to the hot coil wire before I paid for a ECU/PCM.

RwP

 

Yes, I checked 12v at the coil with my voltmeter while my wife tried to crank the engine and it had 12v the whole time..

I'm going to try a few junk yards but i doubt I'll find a computer for a truck that old at a junk yard.

 

Which is why I mentioned car-part.com - which is an aggregator of several wrecking yards across the country.

RwP

 

Which is why I mentioned the one I did for $50...it was one of the few on there that listed a price and based on the fact it's a one year only item that seems reasonable.

Steve

 

Hey y'all, I could use some help here. Got a 99 Dakota. 5.2, Automatic, 4x4. Bought it non-running. The guy said it died on him going down the road. He put 2 grand into trying to get it running again and no luck. Its got no spark. It's brand new: Crank position sensor, cam position sensor, cap, rotor, coil, ECU, fuel pump, battery, and alternator. No spark at all. Don't know if it's getting fuel, but I don't smell any. I think there might be corrosion under the fuse box that could be causing the issue, but not sure. Any help is appreciated!