Is my computer dead??
New User
Joined: Sep 2002
Posts: 16
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From: Coppell
Is my computer dead??
I tried to hook up the self diagnostic jumper and meter like described and got nothing, but the needle on my multi tester just stayed at 12v. I also noticed that my throttle sensing solenoid at the back of the carb is not working, and neither are the vacuum solenoids that are mounted at the back of the valve cover (on a 300 I-6). I was wondering if there was a way to check to see if the computer is working, or if the computer was out, would my truck even be able to run? It runs like crap right now.
Moderator
Joined: Jan 2001
Posts: 56,992
Likes: 2,741
From: Virginia
Is my computer dead??
Try to find the EEC power relay. This sends power to the computer when the key is turned on. It's probably a little black box with a white/lightblue, yellow, red, and black/lightgreen wires coming out of it. Sorry, but I don't know where it's located, but I would start looking on the passenger side fenderwell. See if you are getting voltage on the red and black/lightgreen wires with the key on.
Posting Guru
Joined: Jan 2001
Posts: 2,358
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From: Nebraska
Is my computer dead??
What year is your truck? If the computer is under the dash, the EEC power relay is right beside it on the right side.
Another place to check is the small wire coming off the negative battery terminal. This is the direct ground to the EEC power relay. These often become corroded at the connector, and the computer won't work without this ground.
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1995 F-150 Supercab XLT 155" 4x4 M5OD 302
1986 F-150 4x4 NP435 300
Another place to check is the small wire coming off the negative battery terminal. This is the direct ground to the EEC power relay. These often become corroded at the connector, and the computer won't work without this ground.
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1995 F-150 Supercab XLT 155" 4x4 M5OD 302
1986 F-150 4x4 NP435 300
Fleet Owner
Joined: Aug 2001
Posts: 29,941
Likes: 46
From: Drummonds, TN USA
Is my computer dead??
Save yourself a lot of hassle -
Pull the ignition module, and distributor and run them over to a reputable parts house.
The good places will test them for free to see where the problem is.
- And if they want return customers, they don't bull(stuff) around.
I know of two or three around Norfolk that are good with that, but there are only a few people at each store I would ask to run the tests.
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New User
Joined: Sep 2002
Posts: 16
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From: Coppell
Is my computer dead??
I dont think it is my distributor or ignition control module Graywolf. I replaced the ICM about 2 years ago, but the truck hasnt been run for a year and a half. The truck was running fine, then I replaced the grommet on for my PCV valve and the whole truck just crapped out. I am guessing maybe I bumped a wire at the back of the vavle cover (all the wires going into all those solenoids), cause I have NO power going to any of those. Anyone know how to test them? I set up a jumper from my battery and all the solenoids operate freely, I can hear them clicking open and shut, but for some reason there is not any fire going to them. I have checked with the engine on, engine off, warm and cold engine. Cant figure out what is supposed to trigger those to open, that is why I wondered if my computer is dead. However I have checked other sensors and they are getting power. I am SOOOO lost 
New User
Joined: Oct 2002
Posts: 20
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Is my computer dead??
Several years ago, I took my 86 F150 4.9L 4x4 to a local mechanic (retired after 20 yrs as a Ford dealer mechanic but now in business for himself) because my truck was running so rich that black smoke was coming out of the tail pipes and fouling plugs on a regular basis. I had tried numerous carb adjustments but was getting no where. Anyway he tried to hook up a diagnostic tool but said my computer was dead and he couldn't understand how it was running at all. He put in new plugs (again) and adjusted the carb for me but things never got better until I had had enough and disconected the computer entirely, replaced the old intake manifold with an Offenhauser, replaced the single barrell Ford carb with a Holley 390 cfm carb and while I was at it added a set of Clifford dual headers. I spent way too much and I will never get that investment back should I ever sell it but it now runs just like it did when new. Probably overkill for the situation but that is what I did.
