Howdy y'all,

For some reason my 1993 3.0 V6 Montero's (6G72) ignition coil isn't sparking. The ignition coil is new, and I get a 12V positive output on one of the two leads, but the other isn't pulsing either with positive or negative. I checked all the wire looms to find a burnt or loose cable, but found none. The ignition rotor is rotating, so it's not something major, like a broken dist. belt or mechanically related. All the fuses, both in the passenger and engine compartments are OK, and I'm running out of ideas...

PLEASE HELP ME!!

I wrote this before but here goes. Remove four wire connector from distributor. Turn key to on position. test the wires on the harness side for the following:
Black wire---Ground
Red wire-----Battery voltage
White wire---5 volts
Green wire---5 volts
If all is good, reconnect connector and crank engine while monitoring the white and then the green wire. Both should toggle between 0 and 5 volts. A digital meter will average this signal and display 2.5 volts.
Conner

Thanx!!

I searched the Forum extensively and found nothing on how to test the dist. sensor. I did find out how it works, though.

I'm testing the ECU and the dist. sensor, but I'm starting to think that the capacitor (power module) is blown. I can't seem to get my hands on one in Puerto Rico, so I'll go junker surfing this weekend.

Let me know. I think I have a whole coil bracket with all the parts but it has a dead coil (burnthru in the case).

You should see 12v at both the coil + and the coil - (a tad less at the - terminal due to coil internal resistance) with ign on and not cranking, tested from terminal to ground. I think you said no juice at the -. Try testing coil resistance from + to -. Spec is .72-.88ohms. + to HV coil wire terminal is 10.3k-13.9k ohms.

Well guys, here's the lowdown:

Vehicle: 1993 Montero 3.0 V6 (6G72)


1. I tested all four cables at the dist. sensor plug:

Black: 12V Negative
Red: 12V Positive
White: 11.6V Positive at switched on AND at cranking, no pulsing
Green: 11.6V Positive at switched on AND at cranking, no pulsing


2. Tested both cables that go into the Ignition Coil:
12V at positive
None at negative, and no pulse when connected test light to one and the other

3. I found the ECU test port next to the fusebox, under the driver side dash, and got a CONSTANT 12V reading after switching on. Does this mean my ECU is dead?

4. I swapped the power module (capacitor) that is next to the ignition coil for a known working one, and the engine ran fine for about 10min. and THEN DIED. The ignition coil was sparking perfectly for this period, and just died off.

...AND I have NO clue what's wrong with it, or why it worked fine for a while.

Thanx!

With the key on, do we have 12V at the W/B wire and a good ground at the B wire of the power transistor? If so Take a test light with the clip on the positive battery terminal, use the probe end to tap on the white wire at the power tranistor. Do we produce a spark at the coil secondary each time we tap and remove the probe?
Conner

YES, your ECU is malfunctioning. I had the reverse issue, no voltage at all on the ECU test terminals. Here's my post (it has a link to the ECU testing tech article) -No Spark, Question about normal ECU operation...

Conner:

Yes, I have a good 12V+ at the W/B and a good 12V- at the B wire. I tapped the W wire with my test light conn at the + batt terminal, and no spark was produced at the ign. coil secondary.

Needless to say, the engine popped to life this morning and ran flawlessly for about 10min. The problem seems to be intermittent, so I'll have to catch it later. All the mentioned resistances in the last post were up to spec, and the ign. coil is new.

Any ideas? Is my ECU starting to die? Do they die slowly and painfully or just keel over?

Thanx!

I have a 1989 3.0L V6 ECU on my winter project, will this ECU fit my 1993 Montero? It works fine and it's just sitting there waiting for me to have a coincidence of money and free time...do I yank it and plug it in?

Probably not. Look at the numbers on them if they match it will work, I doubt they are the same. I have never tried to run a 3.0 with another comp from a diff 3.0, too scared something would happen, ECUs are not cheap.