that don't make sense how they can not have a ballast resister with 2 pins. they are used on pretty much every mopar. rock auto has the them for $1.78 plus shipping. you could probably use the one with 4 pins but you would just have to use the rights pins because it should have the same resistance.

 

I believe the ones that had two pins had a wire that bypassed the resistor when starting.

 

so does the one with 4 pins.

 

That didn't make a lot of sense to me either. The only reason I can think of is that dodges are somewhat uncommon around where I live. It's the middle of chevy country here. (Warner Gear and the Muncie manual transmission plant were within walking distance of each other). Well that and it seems like everyone is trying to phase out all the parts for these older trucks. The only parts they had on the shelf for my truck were the plugs and wires. I had to order EVERYTHING else from the warehouse (even the cap and rotor!), but they have everything you'd ever need for a chevy in the store.

 

There were 2 types of dual resistors. Thermal and non-thermal. The one in wolfie's diagram is a non-thermal. The thermal ones had .5 and 5 ohms. I would check the resistance in yours to be sure you have the 1.2 ohm type. Charlie is also correct about the bypass wire when starting.

 

The resistor is at exactly 1.2 ohms. The mech said he'll have it in the shop today or tomorrow, but either way I should have it back tomorrow. I can't wait to finally jump in it and go!

 

hey did you find out the spark issue?just curious,my 87 D100 has the same issue,however i can start truck by hot wiring 3 wires.,but i have no interior lights or exterior unless i hot wire them from under the dash.Swapped out 3 ignition switch before hot wire the truck.

 

look at the fusible links.

 

The 87 was 1st year with in fender computer Im on 3rd one. I just developed this issue for first time

 

Depends on what engine and whether originally a Calif vehicle or not. Slant 6 went to computer in 81, 318 with a 2 barrel carb (non Calif) went to that computer behind the battery in 86. 318 4 barrel and 360 had the 4 pin ecu and ballast resistor.
318 went to TBI injection in 88, while 360s were still 4 barrel and 4 pin ecu in 88 yet, went TBI (which was a ****ty setup, they sucked) in 89.
I have an 85 with a slant 6, it had the computer but no more.
1 more thing to check are the fusible links in the wiring harness along the driver side fender well. By the hood hinge. If they blow it can take power away from all sorts of things.
​​​​​​My 85's original under hood wiring was a complete hacked up train wreck. Lots of butchery by the past owner's. It was easier for me to get another harness from the junkyard and go thru it and fix any bad spots that were bad just on account of old age. I got a harness off of a truck that had the 4 pin ecu, it plugged right in to the bulkhead at the firewall. I did alot of untaping, soldering, applying heat shrink tube on mine. I spent alot of time with a wiring diagram and I also wired in an under hood fuse box from a newer vehicle (that fuse box ended up not being from a Dodge) that I pirated out of the junkyard. Everything that used to go through a fusible link now goes thru the new fuse box.
this didn't affect the factory under dash fuse box at all, that is all still there like the truck came when it was brand new. Overkill? Maybe. But I will never have wiring problems again as long as I own this truck unless the rodents attack.
I am restoring this one to keep for a long time too.
Currently even though it runs ok I have another engine sitting in the machine shop as we speak that is headed for this truck.