No Spark After Speedo Change

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No Spark After Speedo Change

Post by macker37 »

Help Needed recently purchased bxgti16v j reg and had to replace speedo and rev counter dials unfortunatly was sold wrong set from a 19td bx. This then caused problems with wires melting since repaired but now the car refuses to start. There is no spark goin to plugs even after replacing coil and ignition pack. Also car put on computer and diagnostic run revealed no problems with ecu all readings come back ok. Running out of ideas any help greatfully recieved.

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Post by tom »

Ok, these ones tend to be tricky because we don't know what you've melted so the only way to go about it is to use logical electrical fault finding techniques.
Guesswork will fail. The coil and ignition pack should be tested on another car first. If they work, your new components can be ruled out. Although I expect that the problem may be in the wiring to the tacho, I am guessing so I would remove this wire from the ignition system. If it has shorted to earth, it could be killing the spark. Mainly, though I would be checking that the correct voltages are present on the supply pins of the ignition unit with the help of the correct wiring diagram, in order to rule out damage to the ignition switch which may well have suffered. There is no easy way, you'll just have to get the meter out and check every connection.
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Post by jeremy »

I'd have thought there are 2 possibilities - one is that the system isn't getting a signal to spark - and the second is that the amplifier system isn't working.

The spark is probably triggered by a TDC sensor rather like an ABS sensor which will generate an impulse when a mark on the flywheel goes past it. This is then fed to the ECU, processed and passed to an amplifier which will handle the highish current required by the coils.

The TDC sensor is on the top of the flywheel/clutch housing. As a first step disconnect it and see if you can measure its resistance. Open circuit - you've found your problem. If it measures OK make sure its in its proper position and its wiring is sound. I think you will be able to trace it back to the ECU plug. This may be covered in the ECU test procedure - but that may not detect if its misplaced - as the test is carried out with the engine stationary - so no pulses from it are measured.

Have a look at Bob Smith's site - under electrical is the whole layout for a 16 valve and the fuel injection is an official Citroen manual.
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Post by macker37 »

Well cheers for prompt reply lads will check given solutions and let you know how it goes. Thanks also for valuable links.
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Post by m_2975 »

There is an ignition module that is used to start the coil and is fed from the tdc sensor. The ignition module is a flat block looking thing with a connector on the bottom of it. It will be behind the batery mounted on the wall.

They are touchy little things and can easily be broken. Put it into another car and try. Don't put a good one in the car as it might break it too.

My Cars:
'93 BX 19GTi Sedan 5M
'89 BX 19TRI Estate 5M
'89 AX GT(With EFI) 2door 5M
In the Family:
'74 SM IE (Fully Restored) 5M
'90 BX 19TRI122 Sedan 4A
'02 Xantia Exclusive Sedan 4AA
'06 C5 2.2HDi Estate 6A