pellert Posted June 30, 2015 Share Posted June 30, 2015 Evening all,A real numpty question for you. After 7 months I tried to fire up the car on Saturday. As you can probably guess it wouldn't start - no spark.There is no voltage to the coil whilst cranking.Does anyone have any ideas?Cheers Paul Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 30, 2015 Member Share Posted June 30, 2015 What sort of ignition system?Do you have a multimeter (or did you test that feed some other way)?Jonathan Link to comment Share on other sites More sharing options...
pellert Posted June 30, 2015 Author Share Posted June 30, 2015 Checked it with a multimeter. I should also say that last November I replaced the Crankshaft Sensor, new plugs, leads and new coil. Everything was fine at that time.I have a MBE 956i ECU, and a standard coil with amplifier, running on webers.Paul Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 30, 2015 Member Share Posted June 30, 2015 What's the battery voltage while cranking?And/or what happens if you try to jump start it from another car with the engine running fast?Jonathan Link to comment Share on other sites More sharing options...
pellert Posted June 30, 2015 Author Share Posted June 30, 2015 Thanks Jonathan, I will try that tomorrow night and report back.Paul Link to comment Share on other sites More sharing options...
andy_h Posted July 1, 2015 Share Posted July 1, 2015 Do you have a master cut off switch (red key thing)? Check all connections and possible short out to prove its not the switch. Link to comment Share on other sites More sharing options...
pellert Posted July 1, 2015 Author Share Posted July 1, 2015 Hi Andy, no master cut off. I am slowly going through the wiring and checking continuity. I am going to have to go back to Caterham and see if they have a pin out diagram for the ECU. The circuit diagram I have bears no resemblance to the ECU fitted.cheers. Paul Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 1, 2015 Member Share Posted July 1, 2015 Please can I have a copy of the diagram?Jonathan Link to comment Share on other sites More sharing options...
pellert Posted July 1, 2015 Author Share Posted July 1, 2015 Yes you can, I will get it scanned at work and email it to you. Please let me know your email address.Cheers PaulBy the way, the battery voltage is 12.81v, with ignition on, fuel pump running it drops to 12.61 and when cranking it drops to 11v. I wasn't able to get jumps leads and a car to it, but I did put a 'jump start' battery on it. With exactly the same results. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 2, 2015 Member Share Posted July 2, 2015 I think 11V on cranking is enough to keep the ECU working. (Has anyone ever seen problems above 10.5V?)Private Mail sent.Jonathan Link to comment Share on other sites More sharing options...
Paul Deslandes Posted July 2, 2015 Share Posted July 2, 2015 PM me with your email address and I can send you the pinouts. Link to comment Share on other sites More sharing options...
Paul Deslandes Posted July 2, 2015 Share Posted July 2, 2015 Or, better yet........... Ignition only will be the same, just ignore the injector drive and lambda pins Link to comment Share on other sites More sharing options...
Paul Deslandes Posted July 2, 2015 Share Posted July 2, 2015 This might be easier to read.CONNECTOR PIN OUT FOR 956-C ECU PIN NO. SIGNAL DESCRIPTION1 ELECTRONICS GROUND2 ECU SUPPLY +12V3 IGNITION DRIVE 14 LAMBDA INPUT5 THROTTLE REFERENCE (5V OUT)6 SPEED SIGNAL7 AIR TEMPERATURE SIGNAL8 COOLANT TEMPERATURE SIGNAL9 POWER GROUND 1 (BRAID)10 IGNITION DRIVE 211 INJECTOR DRIVE12 SPEED RETURN13 TACHO SIGNAL14 FUEL PUMP RELAY OR SHIFT LIGHT15 THROTTLE SIGNAL Link to comment Share on other sites More sharing options...
Paul Deslandes Posted July 2, 2015 Share Posted July 2, 2015 You should have 12V on one of the pins of the coil (wasted spark?), the other two being alternately switched to ground by the ECU ignition drive signals. If there's no 12V then suspect the power relay in the loom or possibly a fuse. Link to comment Share on other sites More sharing options...
pellert Posted July 2, 2015 Author Share Posted July 2, 2015 Thank you Paul & Jonathan,A quick update, I connected 12 volts direct to the coil, engine fired first time, and every other time I tried it. Just have to diagnose the fault now. Link to comment Share on other sites More sharing options...
pellert Posted July 4, 2015 Author Share Posted July 4, 2015 Paul,My ECU is wired up as follows:1 Pink Coil Pin 22 White I am assuming this is 12Volt supply*3 Purple Coil Pin 46 Yellow Crankshaft Sensor Pin 29 Black Earth12 Slate Crankshaft Sensor Pins 1 & 313 White / Black Tacho Sensor*Is the ECU 12 volt supply coming from the Ignition Switch? Is this something the Immobiliser will immobilise? if so this could be my problem - duff immobiliser.Tomorrow I wil try and connect 12 volts to the ECU direct from the Ignition Switch and see what happens.l Link to comment Share on other sites More sharing options...
Paul Deslandes Posted July 4, 2015 Share Posted July 4, 2015 ECU Pin 1 is ground so I wouldn't expect it to be connected to the coil. The ECU coil drive signals should go to the coil from ECU pins 3 & 10, not 3 & 1. Don't know which immobiliser you have but they normally kill the starter and fuel pump as well as the ignition. Again, not knowing your loom, the coil and ECU will probably be powered via a relay or at least the coil will, the relay being activated by the ignition switch +12V. After market looms often have the relay built into the loom itself. Is power going to the ECU when you turn on the ignition or, because the coil and ECU +12V lines are connected together somewhere, does the ECU just get powered up when you connect your test connection to the coil?Paul Link to comment Share on other sites More sharing options...
pellert Posted July 4, 2015 Author Share Posted July 4, 2015 My immobiliser is a Shurlok EP100. The ECU is MBE 956i.The fuel pump is working and there is power to the starter.Even when I hot wire the coil to start the engine, there does not appear to be a supply to the ECU (I will recheck this is the morning.I cannot find any relays in the loom, unless they are covered in black tape. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 5, 2015 Member Share Posted July 5, 2015 Paul: What's the smart way of testing the ECU other than the ignition out(s)? Earth, feed on the input side and some other pin/ function on the output side?ThanksJonathan Link to comment Share on other sites More sharing options...
Paul Deslandes Posted July 5, 2015 Share Posted July 5, 2015 PaulIf the engine runs with power hot wired to the coil then the ECU must be getting power and running correctly, otherwise the engine wouldn't start. Maybe your loom doesn't have a power relay and power to the coil and ECU are directly from the ignition switch. Pull the connector off the ECU and check either for +12V to pin2 and/or check for continuity between the coil and pin2. If it's o/c then I would check that all the wires are on the back of the ignition switch and then hunt for a relay somewhere.JKunless the engine is being cranked the only active output is the +5V reference to the TPS. This won't tell you if the ECU has a fault, only that it has a supply to it. Ignition and injector drives and, indeed, fuel pump and shift lights are almost always switched to ground so hard to detect a signal without an oscilloscope although you might see something with an analogue voltmeter if you knew what to look for.Paul Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted July 5, 2015 Member Share Posted July 5, 2015 ThanksJonathan Link to comment Share on other sites More sharing options...
pellert Posted July 5, 2015 Author Share Posted July 5, 2015 Paul and Jonathan,Thank you for your inputs, I now believe I have done enough to get me going.There was continuity between the ECU Pin 2 and the ignition switch, and when applied there was 12 volts.There was no continuity between the ECU Pin 2 and Coil, nor between the Coil and ignition switch.I could not find a relay and I didn't want to remove the black tape from the loom to find a broken wire (I will save this for the winter).I have added a wire now to the Coil, connected to a spare contact on the ignition switch and hey ho everything works as it did before.Thanks again Paul Link to comment Share on other sites More sharing options...
Paul Deslandes Posted July 6, 2015 Share Posted July 6, 2015 Sounds like a very good workaround. Nothing worse than having the car in bits whilst the weather is good, they are for driving after all. It might be worth putting a 10A fuse in the new line to the coil unless there's one further upstream, just to give a bit of protection to the wiring.The aftermarket looms have a relay included but you can't miss them as they're standard 1" cube auto types, so you almost certainly don't have one. I'll be interested to know what you find if you do eventually get to the bottom of it.Enjoy the carPaul Link to comment Share on other sites More sharing options...
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