ECU Fuse problems
Discussion
We have a '01 high spec supersport, only 10 k miles and in great nick.
On two ocassions in the last month however, when we've stopped the car - fuel etc and gone to restart the 20amp fuse for the ECU has gone and there's no starter, just a click.
Talked to Nick at Midlands who said this happened, especially if car was running hot. To be fair, second time car had everything on, heater, lights, wipers etc but the 30 amp fuse he suggested just meant that the car wouldn't start 'til it cooled down.
Anyone had this problem and any ideas how to resolve. Not a disaster but a nuisance.
Cheers
Scott.
On two ocassions in the last month however, when we've stopped the car - fuel etc and gone to restart the 20amp fuse for the ECU has gone and there's no starter, just a click.
Talked to Nick at Midlands who said this happened, especially if car was running hot. To be fair, second time car had everything on, heater, lights, wipers etc but the 30 amp fuse he suggested just meant that the car wouldn't start 'til it cooled down.
Anyone had this problem and any ideas how to resolve. Not a disaster but a nuisance.
Cheers
Scott.
Welcome to the K click!
There are 2 main theories why this happens (there are also 2 variants of starter motor it tends to happen with).
1) when the solenoid (which is actauted to engage the starter pinion on the flywheel and also supply +12v to the starter) gets hot (due it's proximity to the exhuast headers, it the actuator rod can expand internally and offer marginally more (physical) resistance than when it's cold
2) combined with (1), due to the miles of wiring in the Caterham loom and the fact that the Multi Function Relay Unit (MFRU) (typically located around/under the ECU) has relatively low current relays where the contacts get pitted over time, means that the current delivered to the solenoid is lower than ideal to provide a strong enough kick to get it to work. This is normally heard as a click, when the low current circuit to power the relay is made (when the starter key is turned/button pressed), but there isn't enough current to 'fire' the solenoid.
Sometimes the solenoid fires, but due to the miles of wiring to the +12v to the starter (which is wired independently of the solenoid), this also has insufficient current to push the motor round.
A blown fuse suggests that due to high resistance, the circuit is carrying too much current and blowing your fuse. This will either be on the feed TO the solenoid/starter, or FROM these two, i.e. the EARTH side of things.
There are a number of fixes to this.
1) Remove all your earth straps and thoroughly clean all connections. Also check the condition of the earth straps themselves. Get some good thick ones on there with good connections on each end, and hopefully bad earth problems will be eliminated.
2) buy a new starter - this doesn't really address any issues, other than lightening your wallet and delaying the onset of the problem again
3) use heat shield around the solenoid/starter. Can stop them cooling though
4) wrap the exhaust headers - can literally kill the packing/wadding in the exhaust and can sometimes lead to the exhaust valves getting too hot
5) replace the +12v feed to the starter from the battery
6) service the solenoid to make sure it's not stuck/dirty, and the hard wired connection between the solenoid and battery is OK and not broken
7) Bypass ALL the caterham loom and install a 30amp relay directly between the starter swtich circuit and the battery and solenoid
Me? I'm doing 1, 5, 6 and 7 this weekend as mine's just started clicking! All parts available from Vehicle Wiring Products, for around £15, depending upon which cables and connectors you go for and whether you get them to pre crimp the leads for you.
Good luck. Loads on BlatChat about this.
There are 2 main theories why this happens (there are also 2 variants of starter motor it tends to happen with).
1) when the solenoid (which is actauted to engage the starter pinion on the flywheel and also supply +12v to the starter) gets hot (due it's proximity to the exhuast headers, it the actuator rod can expand internally and offer marginally more (physical) resistance than when it's cold
2) combined with (1), due to the miles of wiring in the Caterham loom and the fact that the Multi Function Relay Unit (MFRU) (typically located around/under the ECU) has relatively low current relays where the contacts get pitted over time, means that the current delivered to the solenoid is lower than ideal to provide a strong enough kick to get it to work. This is normally heard as a click, when the low current circuit to power the relay is made (when the starter key is turned/button pressed), but there isn't enough current to 'fire' the solenoid.
Sometimes the solenoid fires, but due to the miles of wiring to the +12v to the starter (which is wired independently of the solenoid), this also has insufficient current to push the motor round.
A blown fuse suggests that due to high resistance, the circuit is carrying too much current and blowing your fuse. This will either be on the feed TO the solenoid/starter, or FROM these two, i.e. the EARTH side of things.
There are a number of fixes to this.
1) Remove all your earth straps and thoroughly clean all connections. Also check the condition of the earth straps themselves. Get some good thick ones on there with good connections on each end, and hopefully bad earth problems will be eliminated.
2) buy a new starter - this doesn't really address any issues, other than lightening your wallet and delaying the onset of the problem again
3) use heat shield around the solenoid/starter. Can stop them cooling though
4) wrap the exhaust headers - can literally kill the packing/wadding in the exhaust and can sometimes lead to the exhaust valves getting too hot
5) replace the +12v feed to the starter from the battery
6) service the solenoid to make sure it's not stuck/dirty, and the hard wired connection between the solenoid and battery is OK and not broken
7) Bypass ALL the caterham loom and install a 30amp relay directly between the starter swtich circuit and the battery and solenoid
Me? I'm doing 1, 5, 6 and 7 this weekend as mine's just started clicking! All parts available from Vehicle Wiring Products, for around £15, depending upon which cables and connectors you go for and whether you get them to pre crimp the leads for you.
Good luck. Loads on BlatChat about this.
fergus said:
Welcome to the K click!
There are 2 main theories why this happens (there are also 2 variants of starter motor it tends to happen with).
1) when the solenoid (which is actauted to engage the starter pinion on the flywheel and also supply +12v to the starter) gets hot (due it's proximity to the exhuast headers, it the actuator rod can expand internally and offer marginally more (physical) resistance than when it's cold
2) combined with (1), due to the miles of wiring in the Caterham loom and the fact that the Multi Function Relay Unit (MFRU) (typically located around/under the ECU) has relatively low current relays where the contacts get pitted over time, means that the current delivered to the solenoid is lower than ideal to provide a strong enough kick to get it to work. This is normally heard as a click, when the low current circuit to power the relay is made (when the starter key is turned/button pressed), but there isn't enough current to 'fire' the solenoid.
Sometimes the solenoid fires, but due to the miles of wiring to the +12v to the starter (which is wired independently of the solenoid), this also has insufficient current to push the motor round.
A blown fuse suggests that due to high resistance, the circuit is carrying too much current and blowing your fuse. This will either be on the feed TO the solenoid/starter, or FROM these two, i.e. the EARTH side of things.
There are a number of fixes to this.
1) Remove all your earth straps and thoroughly clean all connections. Also check the condition of the earth straps themselves. Get some good thick ones on there with good connections on each end, and hopefully bad earth problems will be eliminated.
2) buy a new starter - this doesn't really address any issues, other than lightening your wallet and delaying the onset of the problem again
3) use heat shield around the solenoid/starter. Can stop them cooling though
4) wrap the exhaust headers - can literally kill the packing/wadding in the exhaust and can sometimes lead to the exhaust valves getting too hot
5) replace the +12v feed to the starter from the battery
6) service the solenoid to make sure it's not stuck/dirty, and the hard wired connection between the solenoid and battery is OK and not broken
7) Bypass ALL the caterham loom and install a 30amp relay directly between the starter swtich circuit and the battery and solenoid
Me? I'm doing 1, 5, 6 and 7 this weekend as mine's just started clicking! All parts available from Vehicle Wiring Products, for around £15, depending upon which cables and connectors you go for and whether you get them to pre crimp the leads for you.
Good luck. Loads on BlatChat about this.
You knew that I would be along soon Fergus...!There are 2 main theories why this happens (there are also 2 variants of starter motor it tends to happen with).
1) when the solenoid (which is actauted to engage the starter pinion on the flywheel and also supply +12v to the starter) gets hot (due it's proximity to the exhuast headers, it the actuator rod can expand internally and offer marginally more (physical) resistance than when it's cold
2) combined with (1), due to the miles of wiring in the Caterham loom and the fact that the Multi Function Relay Unit (MFRU) (typically located around/under the ECU) has relatively low current relays where the contacts get pitted over time, means that the current delivered to the solenoid is lower than ideal to provide a strong enough kick to get it to work. This is normally heard as a click, when the low current circuit to power the relay is made (when the starter key is turned/button pressed), but there isn't enough current to 'fire' the solenoid.
Sometimes the solenoid fires, but due to the miles of wiring to the +12v to the starter (which is wired independently of the solenoid), this also has insufficient current to push the motor round.
A blown fuse suggests that due to high resistance, the circuit is carrying too much current and blowing your fuse. This will either be on the feed TO the solenoid/starter, or FROM these two, i.e. the EARTH side of things.
There are a number of fixes to this.
1) Remove all your earth straps and thoroughly clean all connections. Also check the condition of the earth straps themselves. Get some good thick ones on there with good connections on each end, and hopefully bad earth problems will be eliminated.
2) buy a new starter - this doesn't really address any issues, other than lightening your wallet and delaying the onset of the problem again
3) use heat shield around the solenoid/starter. Can stop them cooling though
4) wrap the exhaust headers - can literally kill the packing/wadding in the exhaust and can sometimes lead to the exhaust valves getting too hot
5) replace the +12v feed to the starter from the battery
6) service the solenoid to make sure it's not stuck/dirty, and the hard wired connection between the solenoid and battery is OK and not broken
7) Bypass ALL the caterham loom and install a 30amp relay directly between the starter swtich circuit and the battery and solenoid
Me? I'm doing 1, 5, 6 and 7 this weekend as mine's just started clicking! All parts available from Vehicle Wiring Products, for around £15, depending upon which cables and connectors you go for and whether you get them to pre crimp the leads for you.
Good luck. Loads on BlatChat about this.
There can also be a physical connection problem in the cap of the solenoid caused by heat and vibration. I managed to resolder mine a few times. Eventually got the solenoid replaced.
I am not convinced that the supply to the starter (rather than solenoid) has any bearing on the ECU fuse as the starter supply is not fused.
Fergus I don't think you mean "high resistance" as in elctrical resistance as the current would be lower not higher. I think if there is a high resistance in the feed to, or earth from the solenoid, it will just not work.
I think the change to 30 amp fuse should stop it blowing, then OP you'll need to work out if you still have the dreaded click. If so, you will have to work out whether to try fixing/changing the solenoid, putting in the relay fix for the solenoid or sorting out the earths. I am also not convinced of the feed to the starter (not solenoid) being known as a problem, but hey it might!
Bert
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