I have a 1995 land Rover Discovery that is a crank no start. Upon checking it out there is no spark from the coil. I am going through the troubleshooting chart in the manual and tests have made it to test 3 before finding incorrect test results. According to test 3 when you put a voltmeter in between battery positive and the negative lead on the coil you should have 0 volts. While testing with the key off I am getting battery voltage and with key on I am getting .275V. The manual goes from there describing what to look for in terms of possible failures for every other symptom but not for the incorrect readings on those voltages. Any help would be greatly appreciated.

 

Is there not anybody that can give some kind of input on this?

 

Try posting in the Disco 1 forum instead of this general area.

 

Find someone who knows the 3.9 Lucas. There are some here who can help. Maybe change the title to include that and post in D1.

 

"Discovery 1 V8i 3.9L has intermittent starting problem". Search this thread to find similar troubleshooting steps.

 

JohnZo, I have searched that thread and it shows to do what I have already done. There still is no resolution to the fault that I am experiencing in the diagnosis. As a recap:

Air gap on pickup is .35MM
Test 2
V1 is 11.49 volts which is low and it has a charger connected now after these tests were performed.
V2 is 11.06V
V3 is 10.93V
V4 is .001V
Resistance across HT lead is 1.083 K Ohms
Test 3
Positive battery to negative coil is 11.26V
Ignition on positive battery to negative coil is .260V
Cranking engine battery positive to coil negative jumps as high as 3.6V
This is where I am stuck as there is no steps in the manual to take if these readings are incorrect except for no increase while cranking it says to go to next step.
The pickup resistance is at 3,000 Ohms
Test 3

 

kbaker, I am looking at the manual, it says if voltage increases (like yours did to 3.6 V), then go to Test 5. Test 5 is to remove the HT lead from the coil to distributor, fit a new HT wire to the coil, other end hold steady to 6mm from earth at engine and crank to look for spark, if no spark, then fit a new coil and repeat Test 5. Test 6 checks if the rotor is shorting to ground, then replace if bad. Test 7 (the final test) is a visual or continuity test of all the HT components looking for signs of tracking and replacing components (distributor cover, coil, plug wire set, spark plugs, rotor, and insulation cover).

I don't know what your budget is, or the age and condition of your HT parts, but none of those parts are very expensive compared to a couple tanks of gas. At this point, I would probably replace the coil, spark plug wire set, distributor cap and rotor, maybe a new set of plugs while I am in there. Then you know where you stand. How long have you owned the beast? Was it driving well before?

PS. I keep a spare coil, HT lead, spark plug, amplifier, cap and rotor in a bag just in case of emergency. I know the parts are all good because I used them all previously.

 

Thank you for the rehash of what the manual says as I can see that in print in my manual. When you follow a troubleshooting tree to trace a problem you do the tests listed till you find something that tests incorrectly which I have done and at that point the manual does not have a resolution for the failed test. Beyond that there has already been a new module, complete distributor with cap and rotor because you could twist the rotor button with the original distributor installed, coil has been swapped out, high tension lead has been swapped, even though you should stop when you find bad results of the test I have continued past that point as I have listed here but cannot find a reason as to why my test was inaccurate on test number 3.

 

Why did the rotor "button" spin? Was the gear damaged on the old distributor? Are you sure the distributor drive gear inside on the cam shaft is in good condition? Along with related internal parts (e.g. timing chain, cam gear, cam position sensor)? Since the voltage increased for Test 3, that means the rotor is spinning, but is it smoothly spinning in synch when you watch the rotor with the cap removed?

For Test 3, the way I understand the voltage is V (batt pos to coil neg) will be equal to V1 minus V3 measured for Test 2, so close to zero but not exact (Ohm's Law at work). So, 0.26 V is a reasonable value and not a failure, even though it is not exactly zero, it is 0 if you are rounding. The main thing is the voltage increases when cranking, that shows the pick up and amplifier are working, then proceed to Test 5.

If you have a new distributor, it will need to be rotated for correct timing and could prevent starting, but that doesn't matter if Tests 1 and 5 produce no spark. Keep up the good work and we'll get to the bottom of this problem.

 

Thank you for the response JohnZo. The gear was tore up on the previous distributor, when trying to pull the rotor button and giving a slight twisting motion you could feel the gear jump teeth and turn the rotor to the next position in the teeth on the gear. When cranking the motor you can see the rotor turning in the distributor with the cap off and can no longer rotate it by hand after the replacement was installed. I will retest everything and double check the results, now that I think about it I have done the tests numerous times and it seems that on test 3 the voltage from battery positive to coil negative was almost battery voltage so I will verify that.