100amp fuse info!!
Discussion
Some info for anyone who may have had/is having the same symptoms.
Ever since I bought my '96 4.2, the rev counter has been a bit of a hit or a miss. Some times worked, sometimes didn't,somethimes it was all over the place however, when it did work, the car ran alot smoother. Also noticed that on occasions, after a good run, the engine wouldn't turn over as quickly on the starter motor making me think the charging system wasn't 100%.
When rev counters & charging systems are discussed on this forum, the 100amp fuse is always the first port of call......I had checked this fuse several times & it was always in one piece & tested OK on the meter.
Last time I was home I thought f
k it & removed the fuse holder & ran the cable directly from the alternator to the battery and would you adam & Eve it........car runs like a dream, rev counter works perfectly & the battery is always fully charged.
One very happy bunny
Ever since I bought my '96 4.2, the rev counter has been a bit of a hit or a miss. Some times worked, sometimes didn't,somethimes it was all over the place however, when it did work, the car ran alot smoother. Also noticed that on occasions, after a good run, the engine wouldn't turn over as quickly on the starter motor making me think the charging system wasn't 100%.
When rev counters & charging systems are discussed on this forum, the 100amp fuse is always the first port of call......I had checked this fuse several times & it was always in one piece & tested OK on the meter.
Last time I was home I thought f
k it & removed the fuse holder & ran the cable directly from the alternator to the battery and would you adam & Eve it........car runs like a dream, rev counter works perfectly & the battery is always fully charged.One very happy bunny
The fuse has 2 jobs to do.
1. It prevents the alternator getting overloaded, if you pull more than 100 or so amps from it the fuse blows.
2. If the alternator goes spectacularly faulty it prevents the battery being completely shorted out by it.
If number 1 happens you may not have much to worry about. If it's number 2 then wave goodbye to your car.
Even if you remove the fuse get some other kind of cable with a fusible link in in to connect the battery to the alternator.
1. It prevents the alternator getting overloaded, if you pull more than 100 or so amps from it the fuse blows.
2. If the alternator goes spectacularly faulty it prevents the battery being completely shorted out by it.
If number 1 happens you may not have much to worry about. If it's number 2 then wave goodbye to your car.
Even if you remove the fuse get some other kind of cable with a fusible link in in to connect the battery to the alternator.
Interesting. Mine dies a couple of weeks ago due to the fuse. Luckily I had a spare.
Since then, the speedo doesn't read anything sensible until about 25mph. Is that possible to be linked (I hasten to add I don't know much about mechanics
).
Also, it makes sense to carry spares, anyone know a good source (i.e. are they 'specialised'?).
Ta
Since then, the speedo doesn't read anything sensible until about 25mph. Is that possible to be linked (I hasten to add I don't know much about mechanics
).Also, it makes sense to carry spares, anyone know a good source (i.e. are they 'specialised'?).
Ta
Dave_M said:
Interesting. Mine dies a couple of weeks ago due to the fuse. Luckily I had a spare.
Since then, the speedo doesn't read anything sensible until about 25mph. Is that possible to be linked (I hasten to add I don't know much about mechanics).
Also, it makes sense to carry spares, anyone know a good source (i.e. are they 'specialised'?).
Ta
I stock both the standard and the better midi fuse which is encapsulated and less likely to corrode and give problems. Since then, the speedo doesn't read anything sensible until about 25mph. Is that possible to be linked (I hasten to add I don't know much about mechanics
).Also, it makes sense to carry spares, anyone know a good source (i.e. are they 'specialised'?).
Ta
See here
Ideally you want the fuse positioned as close to the battery as possible.
You want to protect as much of the cable as it is the cable that suffers extreme temperature rise on a short circuit.
Having unprotected cable runs is not good.
You also need to bear in mind that the alternator will contribute current to the faulty circuit, so having a fuse near the alternator is good too
I am in the process of completely re-arranging the power circuit on my Cerb for reasons given above.
Just look through all of the salvage TVRs in the classifieds here the amount that have been written off due to electrical fires is staggering.
If it aint electrical, it will be fuel related...
You want to protect as much of the cable as it is the cable that suffers extreme temperature rise on a short circuit.
Having unprotected cable runs is not good.
You also need to bear in mind that the alternator will contribute current to the faulty circuit, so having a fuse near the alternator is good too
I am in the process of completely re-arranging the power circuit on my Cerb for reasons given above.
Just look through all of the salvage TVRs in the classifieds here the amount that have been written off due to electrical fires is staggering.
If it aint electrical, it will be fuel related...
Edited by vroom on Tuesday 7th September 10:20
vroom said:
Ideally you want the fuse positioned as close to the battery as possible.
You want to protect as much of the cable as it is the cable that suffers extreme temperature rise on a short circuit.
Having unprotected cable runs is not good.
You also need to bear in mind that the alternator will contribute current to the faulty circuit, so having a fuse near the alternator is good too
I am in the process of completely re-arranging the power circuit on my Cerb for reasons given above.
Just look through all of the salvage TVRs in the classifieds here the amount that have been written off due to electrical fires is staggering.
If it aint electrical, it will be fuel related...
I thought the fuse was there to protect the cabling and battery in the case of an alternator failure and thus producing an overcurrent, hence it being located close to the Alternator.You want to protect as much of the cable as it is the cable that suffers extreme temperature rise on a short circuit.
Having unprotected cable runs is not good.
You also need to bear in mind that the alternator will contribute current to the faulty circuit, so having a fuse near the alternator is good too
I am in the process of completely re-arranging the power circuit on my Cerb for reasons given above.
Just look through all of the salvage TVRs in the classifieds here the amount that have been written off due to electrical fires is staggering.
If it aint electrical, it will be fuel related...
Edited by vroom on Tuesday 7th September 10:20
ridds said:
vroom said:
Ideally you want the fuse positioned as close to the battery as possible.
You want to protect as much of the cable as it is the cable that suffers extreme temperature rise on a short circuit.
Having unprotected cable runs is not good.
You also need to bear in mind that the alternator will contribute current to the faulty circuit, so having a fuse near the alternator is good too
I am in the process of completely re-arranging the power circuit on my Cerb for reasons given above.
Just look through all of the salvage TVRs in the classifieds here the amount that have been written off due to electrical fires is staggering.
If it aint electrical, it will be fuel related...
I thought the fuse was there to protect the cabling and battery in the case of an alternator failure and thus producing an overcurrent, hence it being located close to the Alternator.You want to protect as much of the cable as it is the cable that suffers extreme temperature rise on a short circuit.
Having unprotected cable runs is not good.
You also need to bear in mind that the alternator will contribute current to the faulty circuit, so having a fuse near the alternator is good too
I am in the process of completely re-arranging the power circuit on my Cerb for reasons given above.
Just look through all of the salvage TVRs in the classifieds here the amount that have been written off due to electrical fires is staggering.
If it aint electrical, it will be fuel related...
Edited by vroom on Tuesday 7th September 10:20
Mine appears to run side by side the cooling pipes which are at ground (-ve).
I'm looking at a fuse / MCCB that will sit on or under the scuttle right next to the battery.
Alternative would be to put it in the -ve side of the battery to ground
I'll post up when I've done it and tested (short circuited) it!
gruffalo said:
Far Eastender said:
FYI - just had my car services at STR8SIX and they replaced the 100 amp fuse with a 125 amp one.
+1The system can now draw a pretty significant amount more amperes... are there any risks associated with doing this?
The Cerbs electrics are very finikey. I've had all sorts of back feed issues since fitting LED rear bulbs on my car without the correct load resistors. When I had the hazards flashing the other day the Ignition would not de-latch!
I suspect that they found something odd back in the day when developing the car and hence whacked a fuse in there.
I suspect that they found something odd back in the day when developing the car and hence whacked a fuse in there.
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