Electrical problem.

[TheRookie]

Ok sorry if I do not describe this well.
I have a 91 XLT with about 95,000 miles. Today I went to pick up my girl friend from work (less than 2 miles) I got out of the truck to get her then we got back in. The truck seemed fine then when she closed her door things got strange. Here is my best description.

The engine will not even attempt to turn over. With the Keys in the "on" position (1 step below crank) the dome light and such got very dim. If i turned the key back one position the lights got bright again. I have tried a different battery that I know to be good and still no luck. I left the key in the "on" position and went under the hood to see if I could figure out the problem. From under the hood I heard a sound I could only describe as a chatter. I narrowed this sound down to the relay pannel just below the main fuse pannel. I then traced the chatter to a specific relay. It was the relay closest to the firewall. After removing this relay the dome light stayed bright with the key in the "on" position. Without the relay the engine would not turn over. I heard one large pop sound when I would try. Obviously this relay does something.

Does anyone know what it is? I am not sure what it may do but I am sure it is important. The bottom of it where the connector goes is GREEN if this helps anyone. I noticed the others were different colors. This is all the investigation I could do so far as the truck is in a pharmacys parking lot.
Thanks for your help.
Mike

 

[Alec]

I'm guessing it's either an ignition, starter, or fuel relay. If that seems to be the problem, replace it

 

[dejello]

You heard the "chatter" sound when the keys were in just the "on" position (one short of start)? Or when when you tried to start the truck?

If it was when you tried to start it, that's normal. It's the starter solenoid (or something like that) clicking. I once had to unplug the wire on it, and "short" it to get my truck started after the battery died, but I doubt you'll need to do that. But mine is in front of the fuse panel, so I may be totally off..

Check your starter, maybe one of the power cables from the battery (could be corroded).

I'm sure there's something I'm forgetting (usually there is), maybe I'll remember it later.. Anyway, hope some of this helps...

 

[TheRookie]

No its not the starter relay. After doing some looking in a shop manual it seems to be an "eec relay" All my experience is with old carbuerated engines. What is an "eec"? Electronic emissions control? would that cause this problem? Thanks for the replies so far.

 

[asp84]

EEC = Electronic Engine Control. This is the relay that allows the engine computer to turn on.

Replace the relay.

Good Luck.
Al

 

[Opera House]

The clue here is you had dim lights

This usually means a bad connection in the battery circuit. The large relay mounted on the fender is the starter relay. The two large terminals on it can be shorted with a screwdriver to power the starter solenoid. This will only be about 10A so no really big sparks. If you do this test (key does not have to be on) and the starter works, you know that the main battery connections are good.

The starter relay will normally give a big click when key is turned to start. If it chatters, it is due to resistance in the battery circuit. When the relay pulls in, the new added load drops the voltage too low to hold the relay in. So it opens and closes and you get this chatter. This can happen to any relay circuit that has a resistance problem. The big terminal of the starter relay that is connected to the battery is a power distribution point. Sometimes a bad connection will form here. Loosen the nut, move the terminals around and retighten. Obvious corrosion should be sanded. The ground connection for the battery is usually at a starter bolt. Often on old vehicles, the ground strap connection from the engine to the frame goes bad. So the engine will crank but lights will be dim. It is often a good idea to run an additional wire rom battery NEG to the frame.

The main power fuses should be puled out and checked. Examine the pins of the fuse for signs of heating and corrosion, Some times the fuse clips become loose and form a bad connection.