F8 fuse in PDC blowes, please help

[horsetrailer]

I am reposting this in the CRD section where it belongs!

Fuse 8 in the Power Distribution Center, called Starter Motor, blows now and then making the engine impossible to start. Have towed to jeep worskhop and they can not find any fault, replace the fuse and everything works for a while. Can anyone give som ideas? Starter Motor? Starter Motor Relay? Igintion Switch or are the more gadgets fed by F8???
Very greatful for any good advice!!!!

 

[Billwill]

I have the 2002 2.5 CRD which is a lot older than your vehicle however I believe the basic circuitry should be the same. I have the complete circuit diagrams for the 2002 CRD, Gas, LHD/RHD Libertys and looking at the citcuitry, Fuse 8 (40 Amp) not only goes to the starter motor but also goes to the ignition switch and then, via the Run position of the ignition switch, goes to the fuse box inside the cabin.
Here it feeds in parrallel fuses 24,25,37,38 and 39..all 10 Amp fuses.
Look up what these fuse supply, obviously a short in any one of these lines should blow the individual 10 amp fuse but maybe if all off these five 10 amp lines are running close to their capacity then they add up to greater than the 40 amp rating or fuse 8.
I believe your problem is in the following areas:
--Starter solonoid drawing too much current
--cabling going from fuse 8 to ignition switch may be shorting to ground
--cable from ignition switch to internal fuse panel going to ground.
If you need more information as regards the circuit diagram or any other questions please send me a personal E-mail with pleasure..I have found quit a few problems regarding the wiring in my 2002 CRD!

 

[horsetrailer]

Excellent !!! Interesting that a 40A feed a number of 10A! If these are all adding up to lets say20-30 A then most probably the 40A will blow when I turn the key! I will unplug the 10A fuses and see what happens. However your idead of a wire that has contact to ground could be the possible answer as the fault comes and goeas and the car has logged some 110 000 km. Will be back with a report following today efforts!

Lennart

 

[Billwill]

You need to check what the 10 amp fuses are doing before you pull them!...some are for things like heated seats but others are probably/definitely for functions needed for the vehicle to run! When I was a Computer Technician I always used to carry some Circuit Breakers with me..all of differant values..so instead of constantly changing fuses while diagnosing a problem...I could reset the CB!..maybe try and get a DC 40 Amp circuit breaker and wire that to replace your 40 amp fuse while you fault-find!

 

[horsetrailer]

Good idea

Theses fuses are extremly expensive so ia he now two pices of wire ans a std european fuse holder which takes ordinary fuses of the kind you almost get paid for to buy! But a CB is ofcourse a better choice but out here on te counntryside you have to use whats found in the shed!

 

[horsetrailer]

Bill, saw you live in South Africa, I would love to be there now, we have about a meter of snow and some days down to -20 degress celsius!