Hi,
I've had a "crank no start " problem for a while now.

It actually was a couple of things.

This is on a 1989 F-150 4.9L 2WD truck.

On the eec relay there is a "high current" 12V coming from a fuse link at the starter selinoid.

This wire back probed at the EEC Relay Connecter is B+ voltage as it should be.

However the "high current" out is only 4.9V!!!

The "low current" voltage coming from the ignition switch is 11.8V.

I have changed the EEC Relay, the eec connector AND the ignition switch.

Still only getting 4.9V out of the high current supply (out) wire????

The ground is good also!

Just to check I took my Power Probe 3 and applied B+ power to the high current out as it is suppose to have and the engine started!!!

I think if I can figure why the power out wire is not getting the full voltage from the high current supply wire I will have this fixed!

Testing by the book it calls this a BAD relay but that is not true in this case?

Strange I know but looking for ideas!!!


Any help on this is appreciated!!!

 

Hi,
Yea, this is a hard one!

I guess a FORD Dealership that has a scope for this old of a truck is next?

Seems no one even has any ideas on this one!

 

The computer runs at low voltage - around 5 volts - if that helps make sense out of all that somehow.