Question regarding the dreaded warning light module on 1988 Esprit

[RichardN]

Hi all,

I've had the problem where the warning light module stops working and all the lights stay on during driving. I took the module to a local electronics specialist who changed the components and checked it worked. He reported that it was doing what it was supposed to but, of course, being a Lotus it's made no difference at all!

I've checked the power coming from the crank to pin 3 which is what is supposed to activate the module and turn the lights off. It shows  12V while actually cranking and the lights go out momentarily but as soon as the engine starts it returns to 0V (or as good as) and the lights come back on. Now the question is, should the crank pin remain at 12V and the problem is there or is the module not staying 'switched'? Without a "good" one to compare it to I've no idea where the problem is.

Can anyone help?

All the best and stay safe,

Richard

[AndyPG]

Hi Richard,

I'm not overly familiar with the module fitted to your car but I would definitely check the following;

• Check for dry/cracked solder joints within the module, especially where wires/parts are soldered to the terminals.
• Check the module socket terminals. Make sure they all grip the module's terminals well and are all clean.
• Check that any ground wires associated with the module are good.

Regards, Andy.

[RichardN]

Thanks Andy,

The module has been rebuilt so I'm fairly sure it's not a soldering problem. The other points you mention seem to be ok as well. As I said the lights go out as you crank the engine over as they should but then come on again. I've no idea at this point if the crank voltage should stay high when the engine is running. If it should then the fault is a wiring one. If not then it's still the module in some way.

Richard

Edited April 7, 2020 by RichardN