Walkthrough 100a fuse changeout
Discussion
Hi all, I thought I’d share my recent experience of symptoms and subsequent repair
I was driving the other day when i noticed the temp gauge dropping off settling at around 50° at the bottom of the gauge, initially I was thinking a water leak had dropped the water level below the sender position but I stopped and checked for any leakage figuring it would be noticeable to lose that amount but there was nothing observable. Also the fans appeared to be working properly and the car seemed to be running fine so I decided to risk the trip home as luckily I was only a couple of miles away.
During the drive home I was watching the temp and then noticed the voltmeter was also low, 11v or so (normally mine reads above 13v mark) I checked the other gauges and everything else was normal.
I got home and confirmed the voltage readings with the multimeter and confirmed the 11v running readings. The battery was also reading on the low side with the car off. After the car cooled I checked the coolant level and it was normal. I decided to do a cold start and warm up to see what happened with me watching more closely. The voltage on start-up cold was a surprise as it was back to over 13 on the gauge but as the car warmed up the voltage dropped off to just above 11 again so that confirmed there was a problem.
I started doing a bit of reading and found out that the temp gauge worked on a voltage return to the gauge and overall voltage on the car being low would have this effect on the gauge reading so focus moved to the charging circuit thinking the alternator had maybe developed a fault. While reading online and my copy of ‘The TVR Griffith and Chimera’ by Steve Heath (a must for any Griffith or Chimera owner, worth its weight in gold!) I saw there was a 100a fuse in the circuit and although I couldn’t see any specific info on these symptoms from owners online the failure of the fuse is noted as being fairly common.
Next thing was to get access to the fuse which it transpired was just behind the starter motor mounted under the engine mounting bracket (easy access!) It was then a case of getting the car up on the ramps santa bought me last Christmas!
And get a look at the fuse housing
Disconnected battery and cracked the housing open and there was obvious heat damage
A quick check confirmed continuity was good but the damage meant that a new fuse and housing were required even if this didn’t turn out to be the cause of my problems. I removed the connections and the fuse parted as soon as I went to remove it.
I ordered the bits and while I waited I cleaned up the connections which identified the cable from the starter solenoid to the fuse was age hardened and even moving it slightly resulted in the insulation cracking so i decided to get a new cable aswell. When they arrived I got back to work fitting the new bits
After fitting, it was time to reconnect the battery and listen for a bang! Fortunately there was no bang and no smoke so next stage was to re-run the cold start to engine fans running, this time after starting and seeing a healthy volt reading at the battery (14.15v) I turned on interior fan and full beam lights to give a good load, volts were still good at 13.7 and temp gauge was reading ‘normal’ (which in TVR speak means good to the nearest 10° lol) after the fans started the volts stayed at a healthy 13.6.
After turning the car off i went and checked the connections for any localised heat but all seemed good
Seems like the issue is resolved
While researching the wiring system I saw a recommendation for Steve Dunford and I must say what a nice guy, he replied to my e-mail within 30mins and furnished me with a full set of good quality wiring diagrams, when I mentioned my issue he confirmed it was common. He also gave me a tip that many had replaced the OE part with a ‘mega fuse’ which is alot more resilient to the vibration on the car. I have ordered one for a future upgrade.
Hopefully this update helps someone in the future!
Thanks for reading
Ian
I was driving the other day when i noticed the temp gauge dropping off settling at around 50° at the bottom of the gauge, initially I was thinking a water leak had dropped the water level below the sender position but I stopped and checked for any leakage figuring it would be noticeable to lose that amount but there was nothing observable. Also the fans appeared to be working properly and the car seemed to be running fine so I decided to risk the trip home as luckily I was only a couple of miles away.
During the drive home I was watching the temp and then noticed the voltmeter was also low, 11v or so (normally mine reads above 13v mark) I checked the other gauges and everything else was normal.
I got home and confirmed the voltage readings with the multimeter and confirmed the 11v running readings. The battery was also reading on the low side with the car off. After the car cooled I checked the coolant level and it was normal. I decided to do a cold start and warm up to see what happened with me watching more closely. The voltage on start-up cold was a surprise as it was back to over 13 on the gauge but as the car warmed up the voltage dropped off to just above 11 again so that confirmed there was a problem.
I started doing a bit of reading and found out that the temp gauge worked on a voltage return to the gauge and overall voltage on the car being low would have this effect on the gauge reading so focus moved to the charging circuit thinking the alternator had maybe developed a fault. While reading online and my copy of ‘The TVR Griffith and Chimera’ by Steve Heath (a must for any Griffith or Chimera owner, worth its weight in gold!) I saw there was a 100a fuse in the circuit and although I couldn’t see any specific info on these symptoms from owners online the failure of the fuse is noted as being fairly common.
Next thing was to get access to the fuse which it transpired was just behind the starter motor mounted under the engine mounting bracket (easy access!) It was then a case of getting the car up on the ramps santa bought me last Christmas!
And get a look at the fuse housing
Disconnected battery and cracked the housing open and there was obvious heat damage
A quick check confirmed continuity was good but the damage meant that a new fuse and housing were required even if this didn’t turn out to be the cause of my problems. I removed the connections and the fuse parted as soon as I went to remove it.
I ordered the bits and while I waited I cleaned up the connections which identified the cable from the starter solenoid to the fuse was age hardened and even moving it slightly resulted in the insulation cracking so i decided to get a new cable aswell. When they arrived I got back to work fitting the new bits
After fitting, it was time to reconnect the battery and listen for a bang! Fortunately there was no bang and no smoke so next stage was to re-run the cold start to engine fans running, this time after starting and seeing a healthy volt reading at the battery (14.15v) I turned on interior fan and full beam lights to give a good load, volts were still good at 13.7 and temp gauge was reading ‘normal’ (which in TVR speak means good to the nearest 10° lol) after the fans started the volts stayed at a healthy 13.6.
After turning the car off i went and checked the connections for any localised heat but all seemed good
Seems like the issue is resolved
While researching the wiring system I saw a recommendation for Steve Dunford and I must say what a nice guy, he replied to my e-mail within 30mins and furnished me with a full set of good quality wiring diagrams, when I mentioned my issue he confirmed it was common. He also gave me a tip that many had replaced the OE part with a ‘mega fuse’ which is alot more resilient to the vibration on the car. I have ordered one for a future upgrade.
Hopefully this update helps someone in the future!
Thanks for reading
Ian
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