My '95 Disco 3.9 has this resistor on the wh/blk wire off the neg coil side, on the way to the ECU. (This is NOT the tune resistor). It tests at 6.8 ohm. Voltage in 12.9 , out 9.8. (The truck now has an electronic distributor and matching coil, but its not HEI.) I think I have read every post on every site, and its still clear as mud. Some say their truck will only run without it. Some say its a spike protector in case of wreck. (I thought that's what the inertia switch is for.) So, it reduces the input to the ECU from 13 to 9.8? Is this correct? If its eliminated, at what risk? I ask not only for my own truck's well being, but to try and clear the air!

 

That resistor is one of many things done to allow the microprocessor in the Ecu to sample the coil voltage and calculate RPM

it might work without it forever, but auto voltage supply is very chaotic especially when an alternator starts to fail. It is definitely not hurting anything. I've never heard of one going bad and would question the diagnostics done by someone who claims they have had one fail.

 

If resistor is removed, will 12.9v trigger the ECU more efficiently and improve the pulse signal to operate the injectors? Is it hazardous to the ECU when resistor removed and a jumper installed? Experimented w/ a jumper, seems as tho it starts faster. Willing to spend $225 for high speed starter, but if a simpler fix is possible.....

 

It is hazardous to the ecu

the resistor limits the current.

the difference in saturation time without that resistor is millionths of a second. Your truck did not start faster without it


And how did you arrive at the diagnosis of either faulty starter or bad Ecu input?

$225 sounds high for a starter. I had the brushes replaced in mine for much less and it's good as new.

 

Thank you for the info. I will leave the resistor in. My truck is not reaching cranking speed to trigger the injectors. (It is not overfueling when cranking and failing to start.) New alternator. Good spark to center of cap, complete new distributor, new coil. Big 1000 cranking battery. New plugs. If one sprays a small amount of starting fluid into intake, starts easily. When thoroughly warm and it can turn over quickly, starts in a second or two. Output from coil to resistor is 12.9v, after resistor 9.8. British Starters gets good reviews by other forum folks. Their's is a high speed gear reduction starter that increases crank speed. Couple of other forum participants have spoken their virtues. Again, thank's for helping.

 

The threshold for that is somewhere around 100rpm. If you have spark it is fast enough for fuel, since it is the same magnetic pickup triggering both

I suspect a bad battery cable from the + post to the underhood fuse box, and once you are at speed the alternator is covering for the voltage drop. An easy way to test is with a dvom check voltage on + and - posts, then they- post and one of the screws under the fuse box cover. This is with the car off. Any measurable drop and you should replace that cable.

 

Hmmm-- will do the cable to box cleanup. Did clean that ground connection, but did not go from there to the box. Need to borrow tester. This is an excellent Rover truck that fell into very unskilled hands. We WILL get it back up to speed!

 

Solved! The security system on '94 and '95 LR Discovery is different than many. You can open the door w/ a key, and crank the starter until forever. No alarm ruckus. But, the security controller interrupts the injector signal. I got the (generic northamerican) EKA code and did the sequence in the drivers door lock. Now the injectors get a pulse signal. It was not cranking speed or resistors. Hope my learnin' w/ all the coaching helps someone else.