I have a 1980 Dodge Macho Power Wagon I have been daily driving the past year. I noticed the electronic ignition module had the sealant out of the backing leaking out & down the firewall. I pulled it off, it has the 4 pins but the wire harness has 5 wires. I have one with 4 pins from a Dart that was running fine a few years back, put it in & it won't start. I went to NAPA & bought a new 4 pin & it won't start with it. I have added a ground wire running to the battery on both thinking the ground was bad but got start up. Really at a loss here on what's making the new one & the old Dart one not work. I can bolt the old melted one on & it runs with it.

Anyone have any ideas on what can be going on with this?

How many pins on the ballast resistor?

2 - 4 pin ecu

4 - 5 pin ecu

If the original was a 4 pin then a 4 pin is what you need, a 5 pin ecu will not work in a 4 pin system, but a 4 pin ecu will work in a 5 pin system.

I just don't want to run with this melted one.

Well, if the ugly one works and the other two do not, then the problem is two of your ecu's are bad and it isn't the one that's ugly.

I would look at the 5 pin connector and make sure the female connections are not loose on the ecu pins, if not then the ecu is bad.

It's got a 2 pin ballast resistor.

I will look at the connectors & make sure they are sliding on correctly.

In 1980 the cars had a 4 pin box, 79 Cars were all Lean Burn ( no Box )

So I guess the trucks would be also.

The 4 pin ECU will work in the 4 or 5 pin wire harness. So you had a 4 pin ECU box on it and now it wont run with the other two 4 pin ECU's you have. Let me ask if this truck has the original eng and was the ECU that worked on it a factory ECU or an aftermarket ECU ? Ron

You have a 2 terminal "single" ballast system so a 4 pin or a parts house 5 pin ECU (has a dummy 5th pin) will work but an OE 5 pin ECU will not. You (simply & correctly) replaced your melting 4 pinner with a replacement 4 pin & no start & that is what ain't making sense on this cuz the only way it would NOT start is if the new ECU is bad (which is possible) but as you know there is no refund on returned electrical parts that are returned as defective as there is no way of them knowing if it actually is defective or if the underlying real cause of the electrical problem has fried the electrical part that was shotgunned in an attempt to diagnose/resolve it (tho on ECU's I ain't thinking of how another issue could fry one if all connections are closed/not open but it could happen). My suggestion: just get another 4 pin ECU or scrub the Hell out of yours but I must admit that is the worst mess I have ever seen!

I does have the original engine & the harness appears to not been modified & it is set-up for the 2 pin, single ballast resistor.

Before you replace the ignition module, do one thing: Disconnect the distributor magnetic pickup connector and reconnect it. This connector can be the source of some very elusive intermittent no-starts that people blame on the control box. The connector is poorly designed. The female portion is simply a round tube with no tangs to positively connect to the male portion. The quick fix is to carefully and gently squeeze the female portion with pliers to crush it slightly and create a better interference fit.

I second the motion. That connector is the reason my Dodge has a replacement pickup coil in the distributor. It wasn't triggering the MSD so it had to be the pickup coil, everything else checked out. Later I found the corrosion in the female part of the chassis connector. Oh, well, it was only an hour and $15.00.

R.

I swapped that one for another while at the local parts house & the second one didn't work either. It ended up being the pin diameter on the ignition module. They are too small around & don't make a connection to the connector on 2 of the 4 pins. You could see where the other 2 slid on the terminal but the other 2 made no marks in it. Took a dial caliper & the new ones were slightly smaller.

Going to order a Mopar Performance unit & try it.

I must have a dozen ECU's for mopars I use Pertronix now or point dist Sick of chasing the Mopar ghost of no start usually due to pickup plate -ECU or bad ground My truck did the same thing backfired and quit turns out it was ground to ECU or should i say rusted away ground.

By the way if you stay with Mopar get a new box just a stock one or a echlin NAPA

I never woulda guessed! I learned something today. I thought something was fishy that the new ECU did not work (I mean it was a simple plug and play deal). EDIT get a chrome one, not an orange (or faster yet go back to your parts house & take your calipers with you)

I never would have guessed either. The guy that runs the parts house called a tech line they have & was on the phone for 15 minutes or so discussing what was going on & it was one of the things they had as a potential issue for a unit that tests good but doesn't work in the vehicle. I was skeptical when he said that then I took it out to the truck & popped mine off & sure enough, my original had larger pins.

I believe I told you that in the 4th post.