Inertia switch - what exactly does it cut?
Discussion
Does it just cut the fuel pump power supply, or does it cut power to the whole MFRU?
I've just installed a new EU2 engine loom from Caterham, and when I flicked my ignition+fuel switch, I didn't hear the fuel pump priming as per usual. A quick prod on the starter button also yielded no results, however the red LED on the Emerald was lit....
On the old loom, I'd removed the inertia switch and hard wired the wires together. Will also do this on the new loom, but surprised to see the starter not working.
Any suggestions from any budding auto electricians out there?
I've just installed a new EU2 engine loom from Caterham, and when I flicked my ignition+fuel switch, I didn't hear the fuel pump priming as per usual. A quick prod on the starter button also yielded no results, however the red LED on the Emerald was lit....
On the old loom, I'd removed the inertia switch and hard wired the wires together. Will also do this on the new loom, but surprised to see the starter not working.
Any suggestions from any budding auto electricians out there?
The interia switch is in the pump power feed from the MFU, hence only effects the pump.
You can see it in tge main loom drawings here:
http://www.the-webbs.com/Electrical%20wire%20diagr...
Its in the top right corner.
You can see it in tge main loom drawings here:
http://www.the-webbs.com/Electrical%20wire%20diagr...
Its in the top right corner.
Arnie
Cheers for that. Also found: http://homepage.swissonline.ch/TomsSeven/Navigatio... which contains http://homepage.swissonline.ch/TomsSeven/Main/Fuel... which clearly shows only the fuel pump circuit is affected. Looks like the multi meter will be getting some use this saturday morning!
Cheers for that. Also found: http://homepage.swissonline.ch/TomsSeven/Navigatio... which contains http://homepage.swissonline.ch/TomsSeven/Main/Fuel... which clearly shows only the fuel pump circuit is affected. Looks like the multi meter will be getting some use this saturday morning!
The starter, ECU and fuel pump circuits (fuel pump drive comes from the ECU though) are explicit in every way except for grounding. If, and its a big if, you have not earthed the new engine loon to the chassis this may be the problem.
The other thing to remember is that the fuel pump drive from the ECU (assuming Emerald functions in a similar way to MBE) It'll prime the pump for 1/2 second when you power up, and will switch the pump off until the crank sensor detects motion, during which fuel pump drive is reinstated.
On an EU2 K series loom it is also very easy to mix up the crank sensor and coil connectors and this will cause no crank sensor signal to t5he ECU hence no fuel pump.
Finally, the starter button will be an entirely separate fault. Check your engine has an earth strap to the chassis, then check for a permanenet 12v supply on the big terminal of the starter. Fianlly use a bulb or meter to check you get 12v on the solenoid control wire for the starter, when you press the starter button. This process will help you find the problem quite quickly.
Good luck. If you are down my way and need a hand, give me a shout.
The other thing to remember is that the fuel pump drive from the ECU (assuming Emerald functions in a similar way to MBE) It'll prime the pump for 1/2 second when you power up, and will switch the pump off until the crank sensor detects motion, during which fuel pump drive is reinstated.
On an EU2 K series loom it is also very easy to mix up the crank sensor and coil connectors and this will cause no crank sensor signal to t5he ECU hence no fuel pump.
Finally, the starter button will be an entirely separate fault. Check your engine has an earth strap to the chassis, then check for a permanenet 12v supply on the big terminal of the starter. Fianlly use a bulb or meter to check you get 12v on the solenoid control wire for the starter, when you press the starter button. This process will help you find the problem quite quickly.
Good luck. If you are down my way and need a hand, give me a shout.
Fat Arnie said:
The starter, ECU and fuel pump circuits (fuel pump drive comes from the ECU though) are explicit in every way except for grounding. If, and its a big if, you have not earthed the new engine loon to the chassis this may be the problem.
The other thing to remember is that the fuel pump drive from the ECU (assuming Emerald functions in a similar way to MBE) It'll prime the pump for 1/2 second when you power up, and will switch the pump off until the crank sensor detects motion, during which fuel pump drive is reinstated.
On an EU2 K series loom it is also very easy to mix up the crank sensor and coil connectors and this will cause no crank sensor signal to t5he ECU hence no fuel pump.
Finally, the starter button will be an entirely separate fault. Check your engine has an earth strap to the chassis, then check for a permanenet 12v supply on the big terminal of the starter. Fianlly use a bulb or meter to check you get 12v on the solenoid control wire for the starter, when you press the starter button. This process will help you find the problem quite quickly.
Good luck. If you are down my way and need a hand, give me a shout.
ArnieThe other thing to remember is that the fuel pump drive from the ECU (assuming Emerald functions in a similar way to MBE) It'll prime the pump for 1/2 second when you power up, and will switch the pump off until the crank sensor detects motion, during which fuel pump drive is reinstated.
On an EU2 K series loom it is also very easy to mix up the crank sensor and coil connectors and this will cause no crank sensor signal to t5he ECU hence no fuel pump.
Finally, the starter button will be an entirely separate fault. Check your engine has an earth strap to the chassis, then check for a permanenet 12v supply on the big terminal of the starter. Fianlly use a bulb or meter to check you get 12v on the solenoid control wire for the starter, when you press the starter button. This process will help you find the problem quite quickly.
Good luck. If you are down my way and need a hand, give me a shout.
thanks for the tips and the offer of some help. I think a session with a multimeter on some of the MFRU pin outs will solve a lot! I'll also check all my earth connections. I've earthed the loom to the battery in two places, so I *think* this will be OK. The new EU2 engine loom has a shielded feed to the crank sensor. The wires are also blue and red, as opposed to brown/purple and white/black!
Another quick question. On the EU2 engine loom wiring diagram, there are two connections to pinouts 7 & 8 on the MFRU output plug, which terminate at a point labelled 'screw'. I presume this should be +12v (rather than earth), as the MFU pinout diagrams on your site suggest these are 'Permanant 12v (in)'?!
Many thanks
I think you just found the problem. The wires from MFU output 7/8 look to me like they should be grounded. There are no ground refernces on the MFU wiring otherwise, so your relays will not function.
This will effect fuel pump and starter switch together on the EU2 loom (in mild contradiction with my earlier post) so thsi looks like a primary cause of the problem.
Having connected them to +12v, I doubt this has done any damage.
This will effect fuel pump and starter switch together on the EU2 loom (in mild contradiction with my earlier post) so thsi looks like a primary cause of the problem.
Having connected them to +12v, I doubt this has done any damage.
Fat Arnie said:
I think you just found the problem. The wires from MFU output 7/8 look to me like they should be grounded. There are no ground refernces on the MFU wiring otherwise, so your relays will not function.
This will effect fuel pump and starter switch together on the EU2 loom (in mild contradiction with my earlier post) so thsi looks like a primary cause of the problem.
Having connected them to +12v, I doubt this has done any damage.
The MFU pinouts 7&8 (wiring diagram) correspond to pins 6&7 on the MFU connector diagram (http://homepage.swissonline.ch/TomsSeven/Main/MFU.htm) which suggest they are 12v? This will effect fuel pump and starter switch together on the EU2 loom (in mild contradiction with my earlier post) so thsi looks like a primary cause of the problem.
Having connected them to +12v, I doubt this has done any damage.
I'm confused now? The two sources seem to contradict each other. I'm guessing the MFU schematic is correct, as the relay needs a low current 12v feed to open the circuit to the big daddy 12v feed. From http://homepage.swissonline.ch/TomsSeven/Main/Fuel... it suggests pins 6/7 are 12v, not earth?
oops, hijack alert...
Actually it is a little know fact of Caterham development that Jez Coates was an EE "doc" Smith fan. The inertia switch actually cuts inertia. That's how caterhams go so quick.
As with most Caterham developments though it was a bit half-arsed so Jez never managed to get it to completely cut inertia, just reduce it a little.
Bert
Actually it is a little know fact of Caterham development that Jez Coates was an EE "doc" Smith fan. The inertia switch actually cuts inertia. That's how caterhams go so quick.
As with most Caterham developments though it was a bit half-arsed so Jez never managed to get it to completely cut inertia, just reduce it a little.
Bert
fergus said:
Fat Arnie said:
I think you just found the problem. The wires from MFU output 7/8 look to me like they should be grounded. There are no ground refernces on the MFU wiring otherwise, so your relays will not function.
This will effect fuel pump and starter switch together on the EU2 loom (in mild contradiction with my earlier post) so thsi looks like a primary cause of the problem.
Having connected them to +12v, I doubt this has done any damage.
The MFU pinouts 7&8 (wiring diagram) correspond to pins 6&7 on the MFU connector diagram (http://homepage.swissonline.ch/TomsSeven/Main/MFU.htm) which suggest they are 12v? This will effect fuel pump and starter switch together on the EU2 loom (in mild contradiction with my earlier post) so thsi looks like a primary cause of the problem.
Having connected them to +12v, I doubt this has done any damage.
I'm confused now? The two sources seem to contradict each other. I'm guessing the MFU schematic is correct, as the relay needs a low current 12v feed to open the circuit to the big daddy 12v feed. From http://homepage.swissonline.ch/TomsSeven/Main/Fuel... it suggests pins 6/7 are 12v, not earth?
Another example of Caterham's lack of attention to detail. Don't even get me started on how little knowledge their parts department have...
PS there is no inertia connection on replacement EU2 engine looms!
Fat Arnie said:
On what pin is the ground connection to the MFU + 12V feeds some reference? Is the only ground on the MFU Input side?
HAve you pulled the MFU apaert to see which relays are operating (an if not to meter them out?)
ArnieHAve you pulled the MFU apaert to see which relays are operating (an if not to meter them out?)
Car running fine now. Due to no 12v feed to the relays beforehand. Grounds on the 'output' side as below.
For reference, the fuel pump utilises the ECU ground on the low current part of the relay ('input' MFU pin 1: black/purple wire) and the 'heavy' current part of the relay is grounded through the fuel pump, ('output' MFU pin 4: yellow/green thick wire)
http://homepage.swissonline.ch/TomsSeven/Main/Fuel...
Starter: 'low' current = grounded back to dash after coming out of the dash mounted starter button, through Input MFU pin 6, out from pin 4 (black/white) then back to the dash through the big grey engine loom to main vehicle loom plug.
The heavy current circuit is grounded after sending 12v to the sarter solenoid, back to the block.
http://homepage.swissonline.ch/TomsSeven/Main/star...
Unervingly, I did notice that when I started the car, there was a pool of water (albeit w/o coolant in it) forming under the car. I think this is from where I had a hose on the engine directly to clean it after the fire, and it must have got into the bell housing and have been flicked out by the flywheel when the engine was going. Depending on how much got in, I may need to get everything bloody hot to help it evaporate!!
chrs
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