One More Time,
You would think they would make this a 'Sticky' by now...
1. Get yourself a test light with a bulb.
Looks like an ice pick with a bulb in the handle and a wire coming out of the handle.
Around $6 at the parts stores.
DO NOT GET THE LED VERSION.
2. Hook Test light WIRE to your battery NEGATIVE terminal.
Probe the Positive terminal to see if the test light is working.
3. DISCONNECT your coil connector from the ignition coil.
4. Probe the 'Red' wire terminal in the coil connector (Disconnected from the coil).
Turn the key switch to the 'Run' position, and see if you get a 'Light' at the tester.
This will tell you if the Ignition fuse, Ignition Switch, Factory Tach and all those little connectors under the dash are working,
And if that power is getting out to the ignition coil.
You do NOT get a light at the coil connector 'Red' terminal, then you have an issue INSIDE the Jeep, or with the fire wall connector, or resistor wire.
5. GET ANYTHING YOU DON'T WANT PINCHED, SMASHED, CUT OFF OR OTHERWISE DAMAGED OUT OF ROTATING PARTS OF THE ENGINE.
6. Have someone CRANK the engine (Key Switch to 'Start' position) and probe that same 'Red' wire terminal while cranking the engine.
You should get a 'Light' at the tester.
*IF*... You do NOT get that light when cranking,
Then you have an issue with the 'Red' wire on the small terminal of the starter relay marked 'I'.
That wire connected to the 'I' terminal on the starter relay goes over to the ignition coil 'Red' wire terminal to supply increased voltage to the coil while cranking.
Now you have Tested, and hopefully VERIFIED the power circuits to the ignition coil.
7. Move the tester wire to the POSITIVE (+) battery terminal and clip it on there.
Touch the Negative battery terminal to verify the tester is working.
8. PROBE the COIL CONNECTOR 'Green' wire terminal.
You should get a 'Light' showing the electrical 'Ground' path to the module, and... ->Through->... the module is working.
The coil electrically 'Grounds' by passing through a switch in the module.
If the 'Green' wire circuit is broken, corrosion, broken wire, whatever,
The coil can't 'Ground', and the module can't switch the coil 'On' and 'Off' to make it fire the plugs.
You SHOULD get a bright 'LIGHT' when you probe the 'Green' wire terminal.
*IF* you do NOT get a 'Light' then either the 'Green' wire circuit between coil connector and module is broken,
Or the 'Black' wire from module to distributor housing is broken,
Or the distributor is no longer making ELECTRICAL contact with the engine block.
(Mechanical Contact and Electrical Contact are two entirely different things)
9. Pull in anything you don't want mangled by the engine when it cranks,
And crank the engine while probing the 'Green' wire at the coil connector.
If you get a 'Flashing' light, then it's probably the coil, coil wire, distributor cap, rotor that isn't working correctly since a flashing light means the ignition module is trying to fire the ignition coil like 'Normal'...
If you DO NOT get a flashing light at the 'Green' wire terminal while cranking.
That means the ignition MODULE is not firing.
You need to find out why...
The next tests work with the module, mounted low on the back side of the DRIVES fender, under he washer tank on '78 to '86 Jeeps.
It's usually easier to work on the harness if you unbolt the module and raise it up as far as you can.
10. Connect the tester to battery NEGATIVE terminal, touch the Positive post to confirm the tester is working.
11. Unplug the TWO WIRE connector going to the module, The module side of the wiring will be 'Red' and 'White'.
You need to test the HARNESS SIDE, which will be a large (10 Ga.) 'Red' and a smaller 'Blue' wire.
Start with the smaller 'Blue' wire on the harness side of the connector,
See if you get a 'Light' when cranking the engine.
Don't worry about power to this one with the key switch in the 'Run' position, it shouldn't be 'Hot' when the key switch is in the 'Run' position, Just when cranking the engine.
If you get a 'Light' when cranking the engine, this power feed to the module is working.
12. Now test the larger 'Red' wire.
This terminal should have power when the key switch is in the 'Run' position, and will sometimes show 'Hot' when the engine is cranking, but that doesn't matter,
Just the key switch in the 'RUN' position is all we are looking for at this time.
*IF*... You got power at the coil in the 'Run' position,
And you DO NOT have power at this terminal in the run position,
Then you have a problem with the 'Splice' between the fire wall connector and where the wire splits into 3 wires (Called a 'Splice') in the harness,
If you found power when and were you needed it,
Then RECONNECT the two wire connector and move on.
13. UNPLUG the 4 wire connector at the module.
Connect your test light to the battery POSITIVE, we are testing the 'Black' wire, HARNESS SIDE.
Probe the black wire, Harness Side, and see if you get a strong, bright 'Light'.
This will confirm your module is getting electrical 'Ground' through the distributor.
That 'Black' wire goes to the distributor and 'Grounds' through the distributor housing.
14. Make up a 'Jumper' wire, just strip the ends of a wire,
Connect one end to the battery NEGATIVE, the other end to the COIL CONNECTOR 'GREEN' terminal.
Then probe the 'Green' wire in the HARNESS side of the 4 wire connector.
You should get a strong 'Bright' light. If you do NOT get a 'Light' then the 'Green' wire between coil and connector at the module is broken somewhere.
From this point forward, you will need a 'Multi-Meter' that is capable of testing for resistance, that means it has an 'Ohms' reading.
IF YOU HAVE A COMPUTER CONTROLLED IGNITION ('83 to '86), SKIP #15 since there won't be a 'Violet' wire in the harness side of the module 4 wire plug.
Move directly to #16 and test the distributor it's self if you don't have a Violet wire in the HARNESS side of the 4 wire module plug.
15. Set your Multi-Meter for 1,000 Ohms, and probe the 'Orange' and 'Violet' wires at the 4 wire connector, harness side.
You should see a reading of 400 to 800 Ohms, with about 625 Ohms being 'Normal' or 'Optimal'.
If you DO NOT get a reading of 400 to 800 Ohms, then you will have to move to the next test.
16. Unplug the distributor from the harness,
Test the DISTRIBUTOR SIDE of the connector, male plugs, you are testing the two running PARALLEL TO EACH OTHER ('Orange' & 'Violet' or 'Black' with 'Orange' stripe and 'Black' with 'Violet' Stripe on some distributors).
Again, you are looking for a reading of 400 to 800 Ohms, with around 625 being 'Nominal'...
*IF*... You DO NOT get the specified reading, the 'Stator' or 'Trigger' winding in the distributor is shot.
*IF*... You DO get the 'Nominal' reading at the distributor, but DID NOT at the module 4 wire plug,
Then you have a wiring problem between the distributor and the module connectors.
Testing the module...
Since there isn't any practical way to test the module other than replacing it,
I suggest you take the module to one of the parts stores and have them test it on the bench.
Since many of the stores DO NOT have properly trained personnel, I would suggest you take it to 3 or 4 of the stores, get a consensus on it's function.
A KNOWN working module is always a good thing to have, but you have to test that module while the vehicle is working, instead of waiting until the vehicle has stopped working since you won't know if your 'Test' module,
Or even a 'New' discount store module is working when you put it in...
Many of these 'Import' or 'China' modules don't work right out of the box, so you can't really rely on a 'New' module to give you a definitive answer.
This SHOULD give you a quick, easy way to find out at least WHERE the issue lays...
The Coil Connector Power test will let you know if the issue is on the firewall side of the coil,
Or in the engine harness it's self.
The module power test will confirm if you are getting power to the module while cranking, and if the 'Start' circuit is powering up like it's supposed to.
The coil ground test will let you know very quickly if the 'Ground Path' is the issue or not.
The Ohms test at the distributor and 4 wire plug let you know if the trigger is working in the distributor,
DO NOT forget to plug in the distributor, module and coil before you go cranking with a new module!
(Ask me how I know that one!