Do I have a bad EEC?
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Joined: Apr 2004
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Do I have a bad EEC?
First off I want to say I love this site. Found it the other night and it has been a big help already.
Now to my problem.
92 F150 5.0 2WD. 200K miles.
The PVC line plugged the other week and oil flooded the engine. (fixed that problem).
Now truck is flooding.
Ran KOEO self this morning. (learned how from reading on this site)
The codes I received.
117, 638, 126, 122, 112, 327, 654, 513, 553, 552, 565, 556, 558, 621, 622, 631, 629, 624.
Check Vref on the ECT sensor (code 117) no voltage should be 5-6V
Check Vref on BP/Map Sensor (Code 126) no voltage should be 5-6V
Check voltage on TPS (code 122) no voltage.
Have no check any of the other sensors.
Read that the EEC regulates the Battery Voltage down to VREf (5-6V).
Since I do not have this voltage at the locations that I tested does this mean the EEC is bad?
I plan on pulling the EEC out tomorrow and see about a replacement.
Any replies are welcome.
Thanks
Now to my problem.
92 F150 5.0 2WD. 200K miles.
The PVC line plugged the other week and oil flooded the engine. (fixed that problem).
Now truck is flooding.
Ran KOEO self this morning. (learned how from reading on this site)
The codes I received.
117, 638, 126, 122, 112, 327, 654, 513, 553, 552, 565, 556, 558, 621, 622, 631, 629, 624.
Check Vref on the ECT sensor (code 117) no voltage should be 5-6V
Check Vref on BP/Map Sensor (Code 126) no voltage should be 5-6V
Check voltage on TPS (code 122) no voltage.
Have no check any of the other sensors.
Read that the EEC regulates the Battery Voltage down to VREf (5-6V).
Since I do not have this voltage at the locations that I tested does this mean the EEC is bad?
I plan on pulling the EEC out tomorrow and see about a replacement.
Any replies are welcome.
Thanks
Lead Driver
Joined: Nov 2002
Posts: 9,557
Likes: 44
From: Concord, NC
Test the wiring between those parts and the computer for continuity. There should be less than 1 ohm of resistance. It could very well be a bad computer, though that is fairly rare, it certainly is possible.
Tuned
Joined: Nov 2002
Posts: 395
Likes: 11
I would diconnect the battery, remove and replace the EEC wire harness connector into the EEC, check to make sure it is clean. Visually inspect the wire harness all over in the engine compartment, check all the vac. lines also. Test your modules and sensors. There has got to be a wire harness problem somewhere.
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Update
Ok. This morning with the EEC harness disconnected from the EEC I tested the wiring to the ECT sensor, The TPS, and The MAP sensor to check for a short to ground. Each wire tested good no shorts to ground and good resistance (from EEC connector to Sensor Connector). Ohms was .1 per my Flute77.
Visually inspected the connectors no sign of corrosion.
Checked and fixed Vac. Lines the other week when had PCV problems. (had one line going to Vac resovoir (sp) broken)
ECT sensor ohms low per Haynes manual. 35K ohms cold.
Thanks EPNCSU2006 and Tripndrag for the responses.
Visually inspected the connectors no sign of corrosion.
Checked and fixed Vac. Lines the other week when had PCV problems. (had one line going to Vac resovoir (sp) broken)
ECT sensor ohms low per Haynes manual. 35K ohms cold.
Thanks EPNCSU2006 and Tripndrag for the responses.
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update-- went thru the steps outlined in the service manual--- when checking the EEC from pin 46 to 40 and pin 46 to 60 suppose to get <5 ohms. - mine showed open circuit. all other test performed on the harness check good. Guess I'll have to go by Napa monday and check to see how much for a rebuilt EEC. In the mean time I've pulled the O2 sensor off (never been replaced), Changing out the ETC sensor.. Going to replace Thermostat with a 192 currently running a 180 (engine temp never even reaches the N in Normal and when termostat opens you can watch the Temp fall on the gauage - replaced Clutch on the fan and Radiator back in the late summer)... Also, going to pull the top plenuim off to see about cleaning the gunk out of it from the stuck PCV. Have already replace the Fuel Pressure Regulator (had someone recommend that to me before I ran the codes).. because of the miles I'll check the Fuel injectors while I have the plenuim off.
Lead Driver
Joined: Nov 2002
Posts: 9,557
Likes: 44
From: Concord, NC
It sounds like you have the same problem I had with the Mustang computer I got - the SIGRTN was shorted out internally, not completing a circuit to ground. I think you've pretty much narrowed it down to the computer.
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Senior User
Joined: Aug 2008
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From: Barrington, Il.
Check ALL of your chassis grounds. I screwed an EEC by missing hooking up a ground wire when converting to MAF on a project - same symptoms.
I'd do that B4 plugging in a re-pop EEC. It won't bring a bad 1 back to life, but could save the replacement.
I'd do that B4 plugging in a re-pop EEC. It won't bring a bad 1 back to life, but could save the replacement.
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