Failed ECU?

[AllenT9]

86 MJ

92 ECM and harness

95 4.0

 

After months and months of repairing rust, rebuilding the 4.0, getting things set up the way I want them. My ASD relay latches in and out. I'm running 2 batteries in parallel, replaced/repaired all grounds, eliminated the fuel pump ballast resistor, cut the latch signal for the ballast resistor bypass relay (not needed with 12v always going to the pump). I've confirmed good battery voltage and ground at ECU. Battery voltage and ignition voltage at ASD relay. The ECU should provide ground to the ASD coil to close it and activate the relay. What I found was a pulsing ground signal from the ECU to the ASD relay. I've Unplugged all loads the ASD relay feeds with no change. At this point I feel it's down to the ECU and a bad capacitor. Any other ideas or thoughts?

[Pete M]

that definitely sounds plausible to me.   probably time to grab a junkyard 'puter and take a shot in the dark.

[cruiser54]

You guys need to grab every ECU you can. 

especially 89 to 90. 

[Eagle_SX4]

I ran into a computer issue on my Eagle when I put the fuel injection back on the '92 4.0 that was in it. It would start and run but only for about 30 seconds then would just die. I think the first computer I tried had some kind of security system on it. I tried a different computer and every is working well now. Definitely try to find a different computer.