Fuse 24 blows when starting

[Mark 1]

Hi Everyone,
I'm new to the group. Looking for some insight on a 99 Ranger 4x4 5speed Manual electrical issue. When I go to start it, fuse 24 sometimes blows. Any thoughts on how to isolate the issue? I have already replaced the starter and the clutch switch. I was wondering if the starter solenoid or relay failing might cause this. Any insight would be appreciated.

 

[bobbywalter]

hamm and a veteran.....awesome. what is 24 listed as?

 

[bobbywalter]

i would ass u me it is the starter relay trigger side from switch.

the switch could be going bad or the relay has an issue. the shorcut is to just swap the relay and see if it stops provided nothing looks like it is cooking.

 

[Mark 1]

i would ass u me it is the starter relay trigger side from switch.

the switch could be going bad or the relay has an issue. the shorcut is to just swap the relay and see if it stops provided nothing looks like it is cooking.

Thanks @bobbywalter. I will try that and report back.

 

[Mark 1]

hamm and a veteran.....awesome. what is 24 listed as?

Fuse 24 is "Clutch pedal position switch, Starter interrupt relay and Anti-Theft" The diagram I have shows that the circuit also flows through the starter relay and starter solenoid.

 

[bobbywalter]

yes. starts at key and dominoes through the safeties till it gets to the starter relay.

usually its a low amp 10 or less. flyback voltage can be a thing in certain scenarios but i cant say for this. sometimes a 15 amp can work but that is a bad idea to double it depending on year.

i would start with the relay.

 

[bobbywalter]

somewhere along the line a aftermarket system or remote start or alarm or something can be in here and the cause somewhere with a stray wire grounding or what have ya... just have to look at it carefully.

 

[Curious Hound]

Blown fuses come from too much current. If you haven't added anything to the circuit, then the problem is most likely that a wire in that circuit has rubbed through it's insulation and is shorting to ground.

 

[sgtsandman]

I'm thinking along the same lines as Curious Hound. I would give the wiring associated with that system a good inspection. If you find a problem, find a solution to prevent that portion of the harness rubbing again. Zip ties, an adel clamp with a rubber lining, something to move the wire away from what it rubbed on and keep it there.

 

[Mark 1]

So,
I replaced the relay. It started perfectly 6 or 7 times while I was in town running errands. However, after driving for 20 minutes and shutting it off for 5 minutes, it blew a fuse. Replaced the fuse, blew again. After waiting for 20 minutes, it started. seems to be heat related. I have so far replaced the clutch switch and the starter relay. Any thoughts n what component in this circuit might be sensitive to heat? I did a thorough inspection of the wiring and did not see anything that looked frayed or worn.

 

[Curious Hound]

We gave you thoughts.

 

[bobbywalter]

testing forward to the starter from the relay for short to ground and back to the switch from the trigger side of relay, shows things are good is what I assume you are saying.

at this point ....

I would bypass the current from the side feeding the trigger side of the relay from the keyswitch with a separate line on a 7.5 amp fuse, manually crank it with key on and see how many licks it takes to get to the center of the tootsie pop.


if it goes good, it's gonna be some hunting....if it keeps burning fuses...will be simpler to find it

 

[Curious Hound]

Up towards the top of your drawing, right underneath the ignition switch. Is there a line splitting off that says it goes to engine controls?

If so, that goes to the PCM. It is possible that we are seeing the effects of bad capacitors in the PCM. Everything else in that circuit is pretty robust and doesn't usually succumb to heat exhaustion.

 

[Curious Hound]

I agree with Bobby. I still think you have a wire shorting to ground somewhere. The capacitors in the PCM will cause funky starting issues. But not normally blown fuses.

 

[Mark 1]

testing forward to the starter from the relay for short to ground and back to the switch from the trigger side of relay, shows things are good is what I assume you are saying.

at this point ....

I would bypass the current from the side feeding the trigger side of the relay from the keyswitch with a separate line on a 7.5 amp fuse, manually crank it with key on and see how many licks it takes to get to the center of the tootsie pop.


if it goes good, it's gonna be some hunting....if it keeps burning fuses...will be simpler to find it

Thanks for the suggestion. I will give that a shot.