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I don't see a CEL in the video you posted either. Mine shines briefly when I first turn the key before cranking. In your video, the engine sounds good after it starts, so it doesn't seem to be getting the signal to the coil. That could be caused by the CKP sensor, or a relay. Less likely, I think is the distributor amplifier or pickup inside the distributor or other ignition system components. Here's a paragraph from the manual: Troubleshoot Lucas ignition system
Thank you for the diagnosis. I have tried this and my V2 and V3 reading were slightly below more than 1V.
Battery 11.9V
V2 and V3 10.6V which is 0.3V lower.
According to the diagnosis ignition switch and/or wiring needs to be checked. Can someone advise what are the common failed parts for ignition switch and/or wiring?
Sam,
There's an electrical switch at the end of the key mechanism. If the contacts are worn from lots of usage, that could cause the low voltage. Together with the low battery voltage could cause weak spark. You need to remove the key mechanism, then you can remove/replace the switch. I notice my key gets really warm after longer drives. That could be a sign the switch contacts are worn and resisting the flow of electricity. The switch contact should be nearly zero ohms resistance, then if the wiring connections are good, not loose or cut or broken strands, between the switch and the coil and battery, you should measure battery voltage at V2 and V3. I have seen new switches for sale, but I have not bought one. Have you tried any of the other tests? How old is your battery?
I don't see a CEL in the video you posted either. Mine shines briefly when I first turn the key before cranking. In your video, the engine sounds good after it starts, so it doesn't seem to be getting the signal to the coil. That could be caused by the CKP sensor, or a relay. Less likely, I think is the distributor amplifier or pickup inside the distributor or other ignition system components. Here's a paragraph from the manual:
Troubleshoot Lucas ignition system
rest of world rover v8 with the 14cux system did not have a bulb check. Its a flag that you can turn on and off if you get in to chip tuning, but its a North American exclusive similar to our lack of tune resistor.
Sam, 11.9 is very low. What is the voltage measured at the battery posts with the engine off?
If your switch contacts are worn, that is something that could change slightly each time you crank the engine. As current flows through the switch it can arc and weld a small bit of the metal contacts. That is where I would start. A new switch is not too expensive and easy access.
Picking up on battery voltage, as RobertF asked above, if it is low, your spark will also be lower voltage and intensity. A new battery is also easy to do.
Thank you guys very much and the information in the forum has been extremely helpful.
I measured them again after the vehicle has been shutoff and sitting in a parking lot for 3 hours.
V1 12.05
V2 10.75
V3 10.75
Sam,
That's what I was thinking too. I think STC1746 is the part number, or STC1746G. That's the hockey puck shaped switch at the end with wires and connectors. That way you won't need two different keys.
If you change the part with the keys, make sure it is for your transmission type (automatic vs manual). The interlock mechanisms are a bit different.
Hi Sam. I would start with the battery terminal connections. Those often corrode. Try to get the clamps and the posts nice and shiny, then connect good and tight. After that, it could be any connection or contacts along the wire run between the battery and the coil (+). I would use some long test leads and an ohm meter to check the overall wires between the switch and battery, then between the switch and coil. The ohms should be very low (subtract the ohms of the long test leads). That should narrow down the part of the circuit that needs help. It probably involves a lot of tedious digging into the wiring.
By the way, have you checked the gap at the magnetic pick up inside the distributor?
Here's another idea. Check the voltage at the switch with the key off and with the key on. There should be battery voltage there. If the voltages are equal and near the battery voltage, the problem is between the key switch and the coil. If the voltage drops to the same low coil voltage, then the problem is between the key switch and the battery.
Hi Sam. I would start with the battery terminal connections. Those often corrode. Try to get the clamps and the posts nice and shiny, then connect good and tight. After that, it could be any connection or contacts along the wire run between the battery and the coil (+). I would use some long test leads and an ohm meter to check the overall wires between the switch and battery, then between the switch and coil. The ohms should be very low (subtract the ohms of the long test leads). That should narrow down the part of the circuit that needs help. It probably involves a lot of tedious digging into the wiring.
By the way, have you checked the gap at the magnetic pick up inside the distributor?
hey sorry for the late reply!
No I have not checked the gap before. Thank you for the advice. It could be the battery terminal connections. I have noticed my battery is slightly below 12V when ignition is on. Perhaps I will change the battery first.
07-20-2021, 12:27 AM
