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So it's been a while but I finally got a complete engine and engine bay wiring harness from an 88 Bronco 5.0 and replaced my old one. Right off the bat I now have a working CEL and it sure seems to be running much better. I can even drive it!!! But, now that I can pull codes, I did. And...

The computer was replaced about 2 months ago. The harness I have is off an 89. Is that compatible?

I ran the test you suggested on IAC. The first 3 all passed. When running the 4th one I got 9v at idle and when I increased rpms it only dropped by 0.1v no matter how much I increased the rpms.

Wouldn't the diode be at least part of the problem if I'm only getting 0.2v out of it?

The only thing I've found is that there is an in-line diode just before the plug for the Idle Air Control Valve and with KOEO I'm measuring 12v in and 0.2v out. I'm reading, and have been told, I should have 5v out because this is part of the 5v Reference Circuit. I can't find a replacement...

Well I think we've narrowed down the problem. I just don't know how to fix it. I ran both of the "Short to ground" test as you explained and I get nothing. Not as in 0 resistance, but nothing at all. I verified that my meter was working so that's not the problem. So now what?

So far everything you listed in your last post has checked out okay but I'm not completely sure how to check for "short to ground" as listed in these 2 tests; -Check Self-Test Input circuit on Pin 48 at computer harness for shorts to ground. -Remove check engine light bulb and check Self-Test...

Okay so here's where I'm at. Once again life got in the way so I finally decided to bite the bullet and I had it towed to a shop that came recommended by another Bronco owner in my area. Turns out the shop owner also has an 81 Bronco of his own. They fixed the fuel pressure problem and rough...

Thanks miesk5 and BroncoJoe19. I won't have another chance to work on it until Friday but I'll let you know what happens. BroncoJoe19 you did read that correctly about my CEL. The problem is I wrote it wrong. It should have read that it "never" comes on. When I pulled the cluster I found a...

BroncoJoe19, I replaced it with a new one and that fixed the biggest issue. Now I'm working on the rough idle and the no power when in gear.

Sorry about not posting my progress over the past few days but life sometimes gets in the way but here's where I'm at: Turns out my fuel pressure test guage was not working properly. My actual Fuel Pressure was about 10 higher than it was reading. So it's actually at 42 KOEO. I also fixed...

Thanks miesk5. One of the other originally listed problems from when I started this thread hasn't been addressed yet and although I'm not sure, I feel like it's related. And that's the fuel pressure. It stays around 30-32 with KOEO, at idle, and when accelerating. I've replaced the...

-Installed new distributor and coil. No change -Fuse 17 is good -Pin 17 has 12v with key on -Pulled the PCM and opened it up --No unusual smells --No damaged or bent pins --No obvious signs of burns or leakage on the circuit board I'll pull alternator in the next couple days and...

I picked up a new coil and distributor this evening. Going to put them in tomorrow.

Paul, I have not replaced the coil but I guess that a good next step. Tiha, It's so bad I can't even drive it down the driveway

Latest update.... -I replaced all the vacuum lines -I replaced the EGR Valve, Solenoid, and Electronic Sensor No change. :-( I did remove the instrument cluster and found the positive lead for the CEL was broken. Repaired it by splicing in a 3/4" piece I cut off the printed circuit of...

Well here's the update........anybody want to buy a Bronco? JK!! Not ready to throw in the towel just yet. -Today I checked continuity of the wires from the ECM to all the engine sensors and solenoids. All were good. -Verified continuity of EEC Test plug wires going to the ECM...

I'm off tomorrow and plan on starting by checking all the EEC grounds, then O2 sensor, and EGR. Any other suggestions...?

Miesk5, By the time I got home last night I was only able to try connecting the SPI directly to the battery to see if I could get any codes. Unfortunately it still did not work. I think I might try running new wires from EEC test plug to their appropriate locations. Tiha, below 3000rpm it...

Forgot to mention that the fuel pressure holds steady for quite awhile after turning engine off. I'll try grounding the single pin connector directly to the battery when I get home this evening and I'll post the results.