Thread: 97 D1 3.9 V8 electrical issues, engine stalls when hot. pulling my hair out!

Originally Posted by PhilipA

I think the one in the engine bay is a diode not a resistor.
I can vaguely recall wondering why they had a diode there as the signal went to the ECU not the other way.

Regards Philip A

Excuse my ignorance but being a diode there what purpose would it actually have? Some sort of protection to prevent current going to where?

Just reading stuff trying to learn.


* Could this be a protection for reverse feed into the ECU? If so i imagine its quite important to keep it there?

Like I said it was one of the last things i done then it ran again. They were covered in crap filled with water. I'll try and get some new ones and replace them especially if it could be protecting the ecu. Only recently I found out that they are a resistor. They have a grease In them which I reckon over 20 years is no longer protecting the insides. From memory it's a resistor not a diode, I still have it here I'll check what it says.
Cheers Jim

Originally Posted by LRJim

Like I said it was one of the last things i done then it ran again. They were covered in crap filled with water. I'll try and get some new ones and replace them especially if it could be protecting the ecu. Only recently I found out that they are a resistor. They have a grease In them which I reckon over 20 years is no longer protecting the insides. From memory it's a resistor not a diode, I still have it here I'll check what it says.
Cheers Jim

I have often thought of doing just what you did Jim. But got confused to its purpose so left it be.
Definitely have had that in my sights as a potential issue. And similar to yourself mine was crusty and filled with crap also.

Withought going outside and looking for it. I googled it and I'm pretty sure it's this "lucas 953066".
It's definitely a resistor that being short protects the ecu.
Some stage today I'm gonna clean it up and put it back in and see what happens.
Cheers Jim

Originally Posted by LRJim

Withought going outside and looking for it. I googled it and I'm pretty sure it's this "lucas 953066".
It's definitely a resistor that being short protects the ecu.
Some stage today I'm gonna clean it up and put it back in and see what happens.
Cheers Jim

Yea mine is the same with an RD i think infront of the numbers. Hard to tell with my eyes.

Originally Posted by DAMINK

That resistor is important.



Source Lucas 14CUX Fuel Injection System – Installation and Diagnostic Notes. - ACT Performance Products - your source for after market TVR upgrades, components and performance accessories.

This is the tune resistor, nothing to do with an inline resistor near the coil. And on mine the tune resistor is buried in the harness under the dash.

Originally Posted by LRJim

Withought going outside and looking for it. I googled it and I'm pretty sure it's this "lucas 953066".
It's definitely a resistor that being short protects the ecu.
Some stage today I'm gonna clean it up and put it back in and see what happens.
Cheers Jim

If it is inline with a white wire it is shown on mine as a "suppressor", and simply shunts to ground. There are a couple of variations depending on year of manufacture, accessories and manual or auto trans.

Originally Posted by Old Farang

If it is inline with a white wire it is shown on mine as a "suppressor", and simply shunts to ground. There are a couple of variations depending on year of manufacture, accessories and manual or auto trans.

Well I've put them back In after giving them a good clean. No dramas it runs fine if not a little more stable. I read somwere that 1 is the wire that sends the RPM to the ecu, I don't know about the other one. I'm guessing the resistor or suppressor helps stabilize the signal to the ecu. I'll have a closer look and see I the other goes to ground or somewhere else.
You can't tell in the pic but one has 2 wires in and 1 going out might give a better idea what their for.
Cheers Jim