99 F-250 electrical issue

[Smokin 6.0]

I’ve got a 99 F-250 that I can’t get to start it has no voltage to the inertia switch for the fuel pump.. sits there and cranks but won’t fire.. also when I turn the key on there’s a few relays that chatter in the under dash fuse box. Also the dome light relay clicks on and off unless you pull it.. if you pull it it all stops. And if you have the relay out and hold the unlock button down the dome lights come on and stay on as long as you have the button down.. any help is greatly appreciated

 

[Magnum PD]

Have a good ground?

 

[Smokin 6.0]

That’s what I’m wondering what would be the best way to go about checking that

 

[Arisley]

What is the battery voltage. Check with the key off, then with the key on then while cranking.

 

[Smokin 6.0]

Have good voltage. Just hooked up a scanner to it and I’m getting no response from the PCM. Is there anyway that I could have a ground issue and not a bad PCM or will the PCM still communicate with a ground issue. Where should I go from here

 

[Smokin 6.0]

Any ideas

 

[Arisley]

What are you calling good voltage?

 

[Smokin 6.0]

11.5v

 

[Smokin 6.0]

Also there are a few fuses that if I test with a test light the interior lights start to flash like I’m providing it a path.. maybe GEM module ?

 

[Smokin 6.0]

I tried a known good PCM and no change

 

[Smokin 6.0]

Ok so I put a Titan Snapon scanner on it and get a low voltage airbag code and a airbag indicator light fault.. that was it... then when I hold the unlock button down and run a diag on it I get the same airbag faults and 11 GEM faults for all kinds of relays.

 

[Arisley]

11.5 is low volts. Charge the batteries.

 

[fastersteve]

^ THIS!

12.2 volts is low..these trucks are very sensitive to low voltage. When you get it started check the alternator too. It should put out 14+ volts.

 

[Smokin 6.0]

I will put good batteries in it tonight and keep you posted.. thanks for the help so far.. I figured 11.5 was ok at least to start it

 

[Smokin 6.0]

Figured it out but I was a very odd thing. The PCM diode was not making good contact.. cleaned it up and put it back in and it fired up.. still having the issue with the dome lights flashing and also the window won’t roll down j less the lock button is held down.. Wierd.. still haven’t changed batteries but that’s next

 

[Arisley]

I forgot all about that diode. That will do it, probably the first time it has been removed since Ford put it in there.

 

[Smokin 6.0]

Probably.. now I’m having issues with my 05 randomly dieing.. when it rains it pours. It will just shut off and idle.. it’s lugs for a second and dies. And if I’m cruising and let off the throttle it dies sometimes..

 

[ghohouston]

On the 6.0, try unplugging the i.c.p. sensor and see if it still occurs.

 

[Smokin 6.0]

That’s what I’m gunna try I looked and the plug doesn’t have oil in it so it’s not a obvious icp sensor issue. Will see what happens when it’s unplugged

 

[Smokin 6.0]

Yea unplugged the icp and doesn’t seem to change anything it runs rough but doesn’t die sounds more like it’s surging then recovers