Electrical problem
Author
Discussion

monty quick

Original Poster:

230 posts

257 months

Sunday 11th August 2013
quotequote all
Car (T350) was running fine then died. All the signs were flat battery (dim indicators, would hardly turnover, etc. left it a while and it started (just) ran for a while then died again. Although the battery was fine when I set out (it had been on the Accumate) it is definitely now fairly flat. No warning lights, no fault codes. If the 125A fuse blows or alternator fails wouldn't there be a warning light? Any ideas?
Thanks

T350 Al

624 posts

212 months

Sunday 11th August 2013
quotequote all
No warning light in either case I'm afraid. Easiest way to diagnose is to get the airbox off and check the 100/125A fuse and go from there. Quick hint though, if you have the standard blade fuse, check it isn't cracked before ruling out the fuse. I've had one with a micro fracture in it that I missed which led me on a wild goose chase!

shep1001

4,617 posts

210 months

Sunday 11th August 2013
quotequote all
T350 Al said:
No warning light in either case I'm afraid. Easiest way to diagnose is to get the airbox off and check the 100/125A fuse and go from there. Quick hint though, if you have the standard blade fuse, check it isn't cracked before ruling out the fuse. I've had one with a micro fracture in it that I missed which led me on a wild goose chase!
This - but just change the fuse they only cost a quid not worth fannying about as you can't always see if the fuse is failing . If its still kippered check the alternator output and your chassis earths. Should be one of those three, quite common on T-cars

monty quick

Original Poster:

230 posts

257 months

Wednesday 14th August 2013
quotequote all
I have had a look at the strip fuse under the airbox. Annoyingly I could not see if it was broken but by the time I took it out is was in two pieces (actually, it was in four pieces - somebody had used 2 x 50Amp strip fuses instead of a single 100Amp !!!)
Can I just check something - can the 125Amp 'bodied' fuse be used instead of the strip fuse (Racing Green offer the bodied fuse as an upgrade but I know several people on the forum have changed the fuse and the carrier). Thanks

shep1001

4,617 posts

210 months

Wednesday 14th August 2013
quotequote all
monty quick said:
I have had a look at the strip fuse under the airbox. Annoyingly I could not see if it was broken but by the time I took it out is was in two pieces (actually, it was in four pieces - somebody had used 2 x 50Amp strip fuses instead of a single 100Amp !!!)
Can I just check something - can the 125Amp 'bodied' fuse be used instead of the strip fuse (Racing Green offer the bodied fuse as an upgrade but I know several people on the forum have changed the fuse and the carrier). Thanks
I believe so, but the holder may be a different size (longer) hence why both are changed together. They are general automotive parts so no need to pay the TVR tax buying via a dealer. Fuses are about £1 and the holders no more than £2.50 each. Surely two 50Amp strip fuses are still rated at 50A not 100A?

Lone Star

138 posts

203 months

Thursday 15th August 2013
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shep1001 said:
Surely two 50Amp strip fuses are still rated at 50A not 100A?
That's quite correct if they were run in series. But if they were run in parallel, then indeed it would effectively be 100A.

monty quick

Original Poster:

230 posts

257 months

Thursday 15th August 2013
quotequote all
I thought it may be an attempt to make the fuse physically stronger but of course it might just be a bodge! I am getting a standard 100A strip fuse and one of the bodied 125A fuses and will see if the bodied fuse can be fitted as a direct replacement. If not I will fit the standard strip fuse to check that is the only problem. If it is, I can change the holder and probably fit a midi-blade fuse later.

VARLEYHYD

2,244 posts

228 months

Thursday 15th August 2013
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Check the 80A fuse in the passenger footwell too.

GV

monty quick

Original Poster:

230 posts

257 months

Thursday 15th August 2013
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Will do - thanks Graham

QBee

22,016 posts

165 months

Thursday 15th August 2013
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Your symptoms are only 100 amp fuse, not 80 amp as well, I think. 80 amp would leave you with almost nothing working.

The 100 amp fuse is, eletrically speaking, between the battery and the alternator. Hence if it is blown you are running on battery. The 100 amp strip fuse can be replaced with a midi fuse in the same holder. You can get them off ebay. More reliable.

Another way to test the 100 amp fuse is with a multimeter. (8 quid from Maplins)
Ignition OFF, multimeter set to 20 volt scale, check the voltage on the main lead at the back of the alternator. Multimeter red lead to alternator, back to engine block. If you have 12.6 volts your 100 amp fuse is fine. If nothing, it is blown.
The other test you can do in the exact same place is to keep your multimeter leads on the asme place and get someone to start the car. If you now see 13.8 volts or thereabouts your alternator is fine. If you egt 11.something volts, your alternator is not doing its job.

monty quick

Original Poster:

230 posts

257 months

Thursday 15th August 2013
quotequote all
Thanks QBEE
I have a multi-mtere but wasn't sure about running the engine with the airbox off.
I will fit the new fuse and test as advised.

monty quick

Original Poster:

230 posts

257 months

Friday 16th August 2013
quotequote all
It was the fuse under the airbox; problem solved and voltages correct - and yes I will now carry a spare and appropriate tools!
Thanks for all of the advice.