No codes from EEC-IV
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New User
Joined: Sep 2000
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No codes from EEC-IV
Hi all,
I own an 86 F-150 with the 4.9 l I6 and 4-spd manual. The motor is carbureted, with EEC-IV and feedback carb.
Lately, I have been plagued with the rough idle problem that many other truck owners seem to have experienced. I have aleady checked for vacuum leaks, and have replaced the distributor, plugs, wires, and coil. Still have rough idle.
I purchased a SunPro code scanner, and hooked it up as directed. The problem is, the STO (self-test output) light is on constantly! When I start a KOEO test, I can hear sounds in the engine comp, but the STO light remains on constantly, so I receive no codes whatsoever.
Does this mean I have a bad computer?
Thanks for your help.
I own an 86 F-150 with the 4.9 l I6 and 4-spd manual. The motor is carbureted, with EEC-IV and feedback carb.
Lately, I have been plagued with the rough idle problem that many other truck owners seem to have experienced. I have aleady checked for vacuum leaks, and have replaced the distributor, plugs, wires, and coil. Still have rough idle.
I purchased a SunPro code scanner, and hooked it up as directed. The problem is, the STO (self-test output) light is on constantly! When I start a KOEO test, I can hear sounds in the engine comp, but the STO light remains on constantly, so I receive no codes whatsoever.
Does this mean I have a bad computer?
Thanks for your help.
Freshman User
Joined: Jul 2000
Posts: 31
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No codes from EEC-IV
Make sure the tester is in the "Hold" position before you turn your key on. After the key is on then turn the tester to "Test". Are you hooking up the extra single wire to the tester? This needs to be hooked up also. Hope this helps.....
Brian & Kathy
1993 F150 Flare Side 5.0L Electric red with bright silver step and ground effects with matching hard cover - PW/PDL tilt, cruise, Captains chairs with lower lumbard, center console.
1989 Lincoln Continental Signature - Cheap to buy - expensive to work on. Signature Series 3.8L - Head gaskets.... I Know!
1989 Probe 2.2L - Fast little car!
Brian & Kathy
1993 F150 Flare Side 5.0L Electric red with bright silver step and ground effects with matching hard cover - PW/PDL tilt, cruise, Captains chairs with lower lumbard, center console.
1989 Lincoln Continental Signature - Cheap to buy - expensive to work on. Signature Series 3.8L - Head gaskets.... I Know!
1989 Probe 2.2L - Fast little car!
Thread Starter
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New User
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No codes from EEC-IV
>Make sure the tester is in
>the "Hold" position before you
>turn your key on.
Did it. The STO light comes on as soon as I hook up the "doghouse" connector.
>After the key is on
>then turn the tester to
>"Test". Are you hooking
>up the extra single wire
>to the tester?
Yep, hooked up the single wire. Still constant STO.
This leads me to believe that I have either a bad computer, or something amiss in the wiring harness.
Steve
>the "Hold" position before you
>turn your key on.
Did it. The STO light comes on as soon as I hook up the "doghouse" connector.
>After the key is on
>then turn the tester to
>"Test". Are you hooking
>up the extra single wire
>to the tester?
Yep, hooked up the single wire. Still constant STO.
This leads me to believe that I have either a bad computer, or something amiss in the wiring harness.
Steve
Postmaster
Joined: Jul 1999
Posts: 3,172
Likes: 4
No codes from EEC-IV
Try using just a jumper wire on the Signal Return Pin & the Self Test Input & using the vehicle Check Engine Light to check for any codes Vs using your Sun Pro . Much easier to use . The problem may be with the scan tool instead of your trucks computer .
Thread Starter
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New User
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No codes from EEC-IV
Thanks for the suggestion. Here's what I did, just today.
Looked carefully at my instrument panel. Saw a space where the "emissions" light should be. Pulled the panel to see if the bulb was bad. There was NO bulb! No only was there no bulb, there wasn't even a bulb socket, nor could I see a place where a socket might have been cut out of the wiring harness! Weird, huh ?
I still think I might have a bad PCM.
More troubleshooting tonight.
Steve
Looked carefully at my instrument panel. Saw a space where the "emissions" light should be. Pulled the panel to see if the bulb was bad. There was NO bulb! No only was there no bulb, there wasn't even a bulb socket, nor could I see a place where a socket might have been cut out of the wiring harness! Weird, huh ?
I still think I might have a bad PCM.
More troubleshooting tonight.
Steve
New User
Joined: Sep 2000
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No codes from EEC-IV
I believe that emission lite has to be in the circuit and good in order to read codes from anywhere. I replaced the bulb in my '90 E-350 with one from RadioShack. Ford couldn't even find a listing for it. It's a 12 volt miniature lamp, 60mA. They were out of the clear one so I bought a pack of three (RS#272-1099, $1.29) and used the red one.
sjb
sjb
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