1997 F-150

While driving truck died.(shut off)...
Tried to restart and nothing...All panel lights come on but no crank..
Good Battery..
Can jump starter on relay..Truck will turn over and fire with key on...
When key is turned off....no start again...unless jump on relay..

Does anyone know what this is????
Please help I have to go to work monday..

Thanks

 

Which terminals on the relay are you jumpng on the relay? The two large ones or the large input post to the small one?

The small post should have battery voltage on it in START. That line comes from the ignition switch via the clutch interlock if a manual or via the neutral safety switch on the transmission if an automatic. That line is also a popular place to place starter disable switches and relays in after-market theft deterrent systems.

Steve

 

The small one two the large one on the right looking at it..

So what do you think it is???

 

Come on guys I cant believe no one knows what this is...

 

Well it turned out to be a fuse...#21 on the inside fuse box...Glad it only cost me .59 cents....Just wonder why it blew out???

 

Well the fuse blew again today...

Any ideas to what might be causing this to happen????

 

it sounds as if something is shorting out.
according to the owners manual on the ford website fuse 21 is for the starter relay (and only the starter relay) which would explain your replacing it and your truck working again.

i might suggest checking the relay to see if it working properly, though your problem seems intermittent so that might pose a difficulty. replacing it all together might be the better way to go.

and if that fails try tracing the wiring from the fuse to the starter and the battery and look for ones that could be rubbing and shorting out.

just my .02$

 

Check your ignition switch and ignition wiring harness. It sounds like the start signal wire in the ignition harness is damaged and shorting out. Fuse 21 supplies power to the start relay when the key is turned to "start". The start relay then energizes the starter solenoid engaging the bendix and turning the engine over.

 

Well I put in another fuse today and it blew again. Being a woman this is not easy for me. I tried to follow wires from the fuse but they all come out together so I dont know where they go. If I am not mistaken the relay is the box on the fire wall where the tow truck guy jumped a screw driver. So what needs to be replaced? I can look up under the steering column and it doesnt look like any wires are bad. I have also looked at the wires on the starter and the battery and they look good. Please help..I just had to get my daughters car fixed and If this is something that I can do I would much rather do it myself money is getting tight. Thanks for all the help

 

When does the fuse blow? Does it blow when you are starting it? Or do you only notice that is is blown when you try starting it and it won't start? FWIW the short that is causing this fuse to blow is after the ignition switch as the fuse is in line after the switch. Do you have any accessories added to the truck? Does your truck have RAPs (Remote Anti-theft)? Does it have an auto or manual transmission?

Regards

Jean Marc Chartier

 

Auto tranny
The fuse only blows out when you turn the ignition to start it.
What is FWIW?
What accessories would that be?
No anti theft.
I took it to the garage monday and they are stumped.
Starter..ok
Selenoid..ok
Ignition switch..ok
Relay..ok

Hmmmmm another delema......