Thursday, July 14, 2011

Fuse 116 blows on ford f-550 Diesel

fuse 116 blows the moment i turn the key to run position, What to do, please help:---

the fuse is 30 amps and is tied into the ignition system then goes to the PCM.
Already Tried:
replacing fuse, still blows. please help.

The moment i turn the key the fuse blows, glow plug light goes out and rest of standard "start up lights

I have seen this problem caused by a short in the engine harness.

Customer :

I fiqured that was the case where does the power travel from the fuse block?

You can verify this by unpluging the engine harness connections for the engine.

Customer :

where are they located?

The connections are attached to the fender liner.

Customer :

what size plugs? how many?

Remove the air filter and air intake tubes then you can follow the harness from the engine to the connections.

There are two connections.

Use caution when moving harnesses as you may cause the short to go away and then not be able to trace the short down.

The most common place for a short to occur is on the intake manifold studs, the harnesses usually become dislodged from there holders then rub though. Also you may need to look under the FICM for the short.

These are the common areas.

Customer :

the ficm is on the drivers valve covers?

Somtimes you can find the harness actually pressed onto on of the studs for the intake, look at the harness well where the air inlet tube going to the intake is , as it can press on the harness causing a short.

Yes the ficm is the moduel on the left valve cover.

Customer :

the plugs on the fender, one is round one is square?

If i recall correctly yes. You can follow the harness visually .

You will have those two connections plus the one going up to engine computer which is between the battery and the fender.

Customer :

definately in the engine harness, do you know of any areas that are very common

RJ :

Please read all my previous posts as i relayed this info to you already . : )

Customer :

ok i will check them.. thanks i wont try to keep you long..

Just look those areas over well.

Customer :

found a white with yellow tracer wire that looks to have been grounded... any other advice.. I assume just reconnecting and running harness away from ground will be ok?

Customer :

got the wire reconnected and it cranks and doesnt blow but will not start any suggestions?

Good job that is the correct wire color . Do all the dash lamps function now. Glow plug lamp etc

did you repair the wire or just unground it ? Make sure that circuit was not damaged enough to cause a open circuit

Customer :

i did get the problem all fixed, found a grounded injector wire also,, thanks for the guidence.



Unplugged the fuel bowl heater and that didn't help.

Pulled the wiring harness off the driver's side valve cover, after someone else suggested it. There was one wire that looked like it had chafed thru and two others were close. Taped them up and it started right up!.

In my case problem was fuel heat connector, it was shorting.disconnected it and cleaned it.number 2 on pic above is its connector


This solved my issue.