Need help. No spark on 1990 Wrangler

I’m working on Drew’s jeep that decided it didn’t want to start anymore. The cap, rotor, plugs, and wires are all replaced recently. I pulled out one of the plugs and connected it directly off the coil… and no spark. So I thought the coil went. Replaced that and still nothing. No spark directly off the coil.

Checked the fuses (all 10 of them or so) and they are all good. There are 4 wires that go into the piece the coil connects to (not sure what its called). I have a yellow, black, orange/black, and a black/green (i think, can’t remember exactly).

The black is obviously ground and has a good ground.
The yellow is the ignition power, and has good 12v with the ignition on.
Black/green (or w/e it is) is a tach signal wire… used it for the remote start.
Orange/black I tested both DC V and AC V and only got around 2v or so while jumping the starter solenoid.

I checked the 2 terminals that connect to the coil and they seem to have some voltage, but very low (around 2-4v roughly).

So I’m not really sure what to go from here… I’m kinda lost. Any help is appreciated.

not really familiar with chrysler ignition systems, but if there is a distributor normally there is a feed from dist. to the coil that triggers it. Sounds like thats your issue to me, since you have good power and ground to the coil, but no fire.

the only connection between the coil and the dist. is the “spark plug wire” And when I put a spark plug directly into the wire off the coil (instead of connecting to the cap) I don’t get any spark.

not sure if it’s the same but on franks 97 we found a broken wire in the main harness that ran from the ecm under the battery tray, reconnected it and now runs great.

I seem to have power going into the Ignition control box but nothing coming out of the coil. I’m thinking it MIGHT be the control box… but I’m not sure.

Control boxes and crank sensors are veryyyy common on these . Is try crank sensor first its on the drivers side rear of the motor where the bellhousing meets block

Yea, I’m going to try to test that tomorrow. Supposedly I should get around 125-275ohms coming off the sensor.

well probably not tomorrow but sometime this weekend.

Pm me if you want ill swing by and help you with it. There’s an auto shut down relay that gives power to the injectors and coil. They share the same power source. I’d be willing to bet that’s the issue.

The ASD relay in the fuse box under the hood is the same as A/C relay and fuel pump I believe. Try to swap relays and see if it changes. The crank sensor is very common on these as well. Next in line is the cam sensor(in the distributor) and then PCM. The two sensors are failry easy to test with a muti-meter. Cam sensor should have a fluctuating 0 to 5 volt signal as you crank/turn motor over, the crank sensor should have an open circuit with an ohm meter. Hope this helps.

I was wondering about that. My 94 had the same thing. However I would think if that was it, I wouldn’t think it would get power to the ICM. The same goes for the crank sensors, cam sensors, etc.

The a.s.d relay is a doubtfully in this case .

if I didn’t have power at the coil I would say the ASD or one of the sensors. but the fact that I have power is what is throwing me off. I have a feeling its the ICM… may have to get it tested if I can.

Does the c.e.l come on when ya key it up ?

I haven’t specifically looked, but I believe that it does. I can check tomorrow.

I’m not talking about the relay being bad. I’m talking about the wire in the harness being bad. I just had the same problem with my 97 wrangler. The wire that gives the injectors and the coil power from the asd was broken in the harness. It’s quite common on the wranglers. Check the section of harness that runs by the battery tray.

Also my c.e.l. keyed on and everything else was fine. When I took the loom off the harness the section that runs by the battery tray was full of mud. That’s where I found the wire that had a green broken spot in it.

I understand what you are saying and I 100% agree… however I have power at the ICM which connects directly to the coil (no harness between). The injectors also have power as the smell of gas when cranking is enough to put you on your ass… lol. If I wasn’t getting power at the ICM then I would be checking the harness… but having power tells me its somewhere between the ICM and the coil.

Hey kenny last time drew was havin issues with the jeep,a few of those relays by the battery tray were replaced as all that wiring seemed to be corroded if it helps any.

Ill look at it but I really don’t think that’s it because I have power to the icm.