WHERE IS THE Electronic Ignition Module in 1991 Mits. Montero located

Likely a gas or spark problem. Spray starting fluid into the air intake while cranking it. If it then runs for a few seconds, it's a fuel problem-maybe the fuel pump, filter, or injector circuit. Check if gas is getting up to the engine.
Buy an inexpensive "spark tester" at a parts store, and check for spark- if no spark, the ignition circuit will need diagnosed- could be the ignition coil, maybe the electronic ignition module-several possibi9lities. Let me know what you find, or if other questions..

You have 3 coils located on top of the ignition module with 2 spark plug wires to each. Usually on that vehicle only one coil dies at once. But if you have no spark at all the ignition module would be the usual problem. There are a couple other unlikely things that can also cause this problem but it will require a repair shop to diagnosis them.

It is possibly a faulty igniter-the electronic ignition module.

Trouble Code 42 indicates that there may be a malfunction in the Electronic Spark Timing (EST) system. During cranking, the timing is controlled by the ignition module and the ECM grounds the EST line. It expects to see no activity on this line at this time. When the ECM enters EST mode, it applies +5 volts to the BYPASS line and expects to see voltage variations on the EST line.
Reasons for the ECM to set Code 42:
1. System in BYPASS mode (i.e. EST line supposedly grounded) but activity sensed on EST line
2. System in EST mode (i.e. BYPASS line driven with +5 volts) but no activity seen on the EST line

Possible causes include:
1. BYPASS line is open or grounded
2. EST line is open or grounded
3. Poor connections between ignition module and ECM
4. Poor routing of EST harness and/or poor quality ignition wires (EMI induced electrical noise
5. Faulty or incorrect ignition module
6. Faulty ECM
7. Faulty Pick Up Coil
8. Faulty Ignition Control Module
9. Faulty Crank Sensor or the Crank Sensor magnet probe could be cracked

It is either under the hood on drivers side under a cover,or behind the glove box area,up in the dash,the ignition module is most likely the cause,most of the time.

check to see if the coil spins when you crank the motor the other thing is the crankshaft sensor is bad

Tried replacing the ignition module with two different ones from a salvage yard. (Most of the distributors in the salvage yard were either missing completely or the ignition module had been removed - must be a very common problem.) Neither one worked.

Purchased a used complete distributor assembly w/warrantee and replaced the one that did not work. Car started immediately.

Suggestion: If one cannot wait for delivery of a new distributor as I could not, (I located one on line for $126.00 w/warrantee) purchase one from a salvage yard w/warrantee, then get a new one if you are going to be concerned about the longevity of the replacement distributor.

Just to get back to basics, the Montero will need to be in two wheel drive to unlock its hubs. To do so the Montero must be placed in reverse and backed-up @ 10-20 feet or so. (during cold weather you may have to drive around abit to heat-up the grease in the hubs so they'll unlock) if this does not unluck them (and it is clearly out of 4WD there is a mechanical problem with the hubs and they need to be rebuilt.
I hope this may have helped,
Tom

The 3.8 engine has an electronic control module under the coil pack that commonly fails.
The harness connecting to that unit is also often the culprit of many ignition problems ... its wiring harness fills with water or other corrosives and rots away. So be nice when removing it from the coil/ignition module... There are numbers visible w/o removing it you will need when searching for one to replace it... 1668994 or something like that... you may want to check prices for a used ignition module/coil pack at car-part.com or mypartshop.com... and try a used one to start...

hello first check your fuses if all okay probaly ignition module goodluck