No Check engine light

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Nov 11, 2004 | 07:43 PM

kcalabr440

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No Check engine light

89 F350 5.8L EFI

Is there anything that would cause the check engine light not to come on when the key is in the on position. I checked the 2 ground wires that are screwed to the front of the truck, i can hear the eec relay clicking when the key is turned on but that is it. After sitting for awhile everything seems to be ok the light comes on and the truck starts. It can run for hours or minutes then dies and no light comes on. Checked for codes and only got running lean.

Any suggestions would be helpful, Thanks

Nov 11, 2004 | 07:51 PM

Franklin2

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From: Virginia

I would start with the EEC relay itself. I think it's about $12.00 at the parts store. Even though it clicks, the contacts inside it may be bad, especially if the computer seems to be dead. This relay feeds the voltage to the computer system and it's sensors.

Nov 11, 2004 | 08:04 PM

kcalabr440

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I changed the relay a few days ago, also took voltage checks and everything seems to be fine. I'm looking at a wiring diagram now, tomorrow i will check voltage between pins 37 and 57 with pin 20, i will also change the relay just in case.

Nov 12, 2004 | 12:43 AM

Franklin2

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From: Virginia

Quote:

I changed the relay a few days ago

Look at the socket it plugs into, and the wiring underneath. Maybe the tangs in the socket are spread out too far or something.

You might want to find some key points to monitor with a voltmeter, and then try to repeat the problem. This may involve rigging the meter inside the cab with wires going out the window and under the hood, especially if it only does it once in awhile.