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Old 11-02-2019, 12:01 PM
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Originally Posted by Luckymac View Post
Which wire did you probe, the tan/yellow or the orange one (looking at the schematic that Kim57 gave you)?

Good Luck, L.M.
I probed the tan/yellow in both places.
As far as I can tell without tearing the whole harness apart that's the one I need.
Afraid to pull it all apart as I may break other wires along the path.
Kim

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Old 11-02-2019, 01:32 PM   #32
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What I would do is repeat the test. I'd start at the distributor end of the circuit.
Turn the key on and then check for any voltage at the connector where the tan/yellow wire connects.
Then check for voltage at the module under the washer reservoir.

If you start at the module under the reservoir and find power, then go to test for power at the distributor, a failing module could stop sending power to the distributor by the time you get there to do the test.

Attempting to follow a wire from under the washer reservoir to the distributor is quite a task and I think your fears are justified.
If you repeat the test starting at the distributor and you get no voltage at the distributor and then get power at the module, I'd run a wire from the module to the distributor as a test wire.
At first, I wouldn't cut and splice a wire into the circuit. I'd temporarily use a tap-a-wire connector on each end to see if that cured the problem. If it does cure the problem and the Jeep starts and runs well, then I'd use a tan wire (I doubt that you'll be able to buy a spool of tan wire with a yellow leader) and run it as best as possible to duplicate how the factory wire might be run. Then, I'd solder and shrink wrap the connections.

If you repeat the teas and get power at the distributor, then no power at the module, I'd say you have either a failing module or computer.

If you live in a non-emission area, you could cut to the chase and buy a HEI distributor.
That would eliminate the computer and everything else that might be giving you problems. It's a direct wire from the battery through a relay that's controlled by power from the ignition switch.

I think you're getting closer. Keep us posted.

Good Luck, L.M.

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Old 11-02-2019, 06:24 PM
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Originally Posted by Luckymac View Post
What I would do is repeat the test. I'd start at the distributor end of the circuit.
Turn the key on and then check for any voltage at the connector where the tan/yellow wire connects.
Then check for voltage at the module under the washer reservoir.

If you start at the module under the reservoir and find power, then go to test for power at the distributor, a failing module could stop sending power to the distributor by the time you get there to do the test.

Attempting to follow a wire from under the washer reservoir to the distributor is quite a task and I think your fears are justified.
If you repeat the test starting at the distributor and you get no voltage at the distributor and then get power at the module, I'd run a wire from the module to the distributor as a test wire.
At first, I wouldn't cut and splice a wire into the circuit. I'd temporarily use a tap-a-wire connector on each end to see if that cured the problem. If it does cure the problem and the Jeep starts and runs well, then I'd use a tan wire (I doubt that you'll be able to buy a spool of tan wire with a yellow leader) and run it as best as possible to duplicate how the factory wire might be run. Then, I'd solder and shrink wrap the connections.

If you repeat the teas and get power at the distributor, then no power at the module, I'd say you have either a failing module or computer.

If you live in a non-emission area, you could cut to the chase and buy a HEI distributor.
That would eliminate the computer and everything else that might be giving you problems. It's a direct wire from the battery through a relay that's controlled by power from the ignition switch.

I think you're getting closer. Keep us posted.

Good Luck, L.M.
Thanks for the info.
Will try testing again to see what I get.
Just looking at the wires it looks like it comes out of the ECU and goes along the left side of the engine with the injector wiring around the front of the head then to the back of the engine and then back up to the distributor.
Kim
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Old 11-02-2019, 07:02 PM   #34
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Probed the wire at the ECU and get 6.6 volts.
Probe the wire at the connection to the distributor and get nothing.
Thinking wire is broken somewhere unless it passes through another relay.
Can we just splice in a new wire between ECU and distributor or do we need to be looking for a new harness?
Thanks for any help.
Kim
The answer is you can splice a wire in but personally I'd avoid if I can. Understand at times you cannot but here is why I wouldn't. First, it's an extra wire that deviates from what the factory did. The service documentation and wire colors make it much easier to troubleshoot. I could see myself working on this car later and being like what did I or someone else do? The second reason is if you find the wire break, sometimes there are more than one wire that is broken. This would allow you to fix all of them at one time. I even suppose you could catch a wire break that could cause a spark and a fire.

Now running a separate wire just to test and experiment, I'd do that. But ultimately it's your jeep and you can do what you want.

I wouldn't do a whole new harness. Just spend some time and find the break. Look for points that the harness is contacting metal, sharp edges. then go from there.

I am a little surprised that your only getting 6.6 volts. Would thing it's closer to 8v. But get the wire repaired and retest.
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Old 11-03-2019, 09:27 AM
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The answer is you can splice a wire in but personally I'd avoid if I can. Understand at times you cannot but here is why I wouldn't. First, it's an extra wire that deviates from what the factory did. The service documentation and wire colors make it much easier to troubleshoot. I could see myself working on this car later and being like what did I or someone else do? The second reason is if you find the wire break, sometimes there are more than one wire that is broken. This would allow you to fix all of them at one time. I even suppose you could catch a wire break that could cause a spark and a fire.

Now running a separate wire just to test and experiment, I'd do that. But ultimately it's your jeep and you can do what you want.

I wouldn't do a whole new harness. Just spend some time and find the break. Look for points that the harness is contacting metal, sharp edges. then go from there.

I am a little surprised that your only getting 6.6 volts. Would thing it's closer to 8v. But get the wire repaired and retest.
Good point about other possible broken wires.
They are all in the original sheathing from the factory so would have to remove it all from the engine to go through them.
Will try and see if I can check it with my test light.
The 6.6v seemed kinda low.
Kim
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Old 11-03-2019, 10:48 AM   #36
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Good point about other possible broken wires.
They are all in the original sheathing from the factory so would have to remove it all from the engine to go through them.
Will try and see if I can check it with my test light.
The 6.6v seemed kinda low.
Kim
What I have learned about troubleshooting wire breaks is don't remove everything. In fact don't touch it...at first. Instead look at the harness from the PCM and work your way back to the cam sensor plug. Look for anywhere the harness has a contact point with something. That contact point may be a bracket, a hose, something that could rub through. Keep in mind that over 100k miles the plastic wrap will rub through on something the least bit sharp. Then it will rub through the wire insulation. Then the wire will get cut or corrode and break. Only when you see a rub point to you inspect the harness at the point closer.

If you remove the harness or move it enough, the contact points won't be obvious.

If that doesn't work, what you can do is go to a connector in the middle of the harness. In this case you don't have one so you could either use a wire piercer probe. Divide the wire in half. Connect it and see is the break to the right or to the left. Then divide again to narrow it in. If you go this route, just make sure you use some liquid electrical table to seal the pierce hole.
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Old 11-03-2019, 03:54 PM
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What I have learned about troubleshooting wire breaks is don't remove everything. In fact don't touch it...at first. Instead look at the harness from the PCM and work your way back to the cam sensor plug. Look for anywhere the harness has a contact point with something. That contact point may be a bracket, a hose, something that could rub through. Keep in mind that over 100k miles the plastic wrap will rub through on something the least bit sharp. Then it will rub through the wire insulation. Then the wire will get cut or corrode and break. Only when you see a rub point to you inspect the harness at the point closer.

If you remove the harness or move it enough, the contact points won't be obvious.

If that doesn't work, what you can do is go to a connector in the middle of the harness. In this case you don't have one so you could either use a wire piercer probe. Divide the wire in half. Connect it and see is the break to the right or to the left. Then divide again to narrow it in. If you go this route, just make sure you use some liquid electrical table to seal the pierce hole.
Thanks for your help.
This information should make things a lot easier.
Kim
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Old 11-04-2019, 10:41 AM
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Stabbed wire at ECU and connection at the distributor with my test light and it shows wire is not broken so I'm leaning toward the ECU being the problem as I only show 6.6v.
We did plug his 4 cylinder ECU and it throws the same code for the cam sensor being bad but highly unlikely as we used three different ones.
Any other thoughts would be greatly appreciated.
Kim
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Old 11-04-2019, 11:47 AM   #39
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Stabbed wire at ECU and connection at the distributor with my test light and it shows wire is not broken so I'm leaning toward the ECU being the problem as I only show 6.6v.
We did plug his 4 cylinder ECU and it throws the same code for the cam sensor being bad but highly unlikely as we used three different ones.
Any other thoughts would be greatly appreciated.
Kim
Let me understand the test you did. Did you run power through wire to light up your test light? For example, clamp your test light to battery neg, touch tip of test light to the pin on the ecu harness (harness unplugged), then have power applied to the same wire at the pin on the cam sensor plug? Is the test light bright?

What is the ohms of that wire? Something is not right..either a test or the wire has a break that changes the ohms depending on the wire movement. How is the pin fitment on the plugs for the ECM and for the cam sensor?
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Old 11-04-2019, 11:37 PM
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Let me understand the test you did. Did you run power through wire to light up your test light? For example, clamp your test light to battery neg, touch tip of test light to the pin on the ecu harness (harness unplugged), then have power applied to the same wire at the pin on the cam sensor plug? Is the test light bright?

What is the ohms of that wire? Something is not right..either a test or the wire has a break that changes the ohms depending on the wire movement. How is the pin fitment on the plugs for the ECM and for the cam sensor?
I used a tester that has its own battery in the handle and probed both ends of the wire. A solid connection will make it light up. If wire is broken then no light.
It only uses a AA battery and light came on just fine.
All connections seem to be nice and tight. No bent pins on either side.
Kind of stumped as to what it can be.
Not sure of the ohms of the wire.
Kim
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Old 11-06-2019, 09:11 AM   #41
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I used a tester that has its own battery in the handle and probed both ends of the wire. A solid connection will make it light up. If wire is broken then no light.
It only uses a AA battery and light came on just fine.
All connections seem to be nice and tight. No bent pins on either side.
Kind of stumped as to what it can be.
Not sure of the ohms of the wire.
Kim
How are the female pins in the connectors? Do any of them look spread? One thing that I would check is the voltage on the orange wire of the crankshaft sensor. It is shared with the cam and speed sensor.

I still think something doesn't add up and I really hesitate winging a PCM at this. The voltage of is a little low on the 8v supply but given that it's a hall effect that may not matter. I have seen connectors where the pins spread and don't grip the male pin well. Or even the wire insulation was cut right by the PCM and corroded. I'd redo those 8v tests and make sure you have good connection. Something isn't right if you have it at the PCM but not at the CAM sensor AND the wire can pass a current. My first thought is connector issues. Could be wire in pin, pins are loose on the board within the PCM (wiggle connector) or pins aren't joining together well enough.

Anyways, some thoughts.
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Old 11-06-2019, 11:44 AM   #42
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Kim57, you state that the voltage out of your ECU is 6.6 volts. I assume you're using a multi meter to determine that.
Rather than using your powered test light, why don't you use your multi meter to look for circuit continuity?
I'm wondering if the powered test light might be giving false positives. It could be showing continuity if only one end of the wire is connected.

If you connect the multi meter to each end of the wire it'll tell you if there's a break and if there isn't a break, it'll tell you if you have excessive resistance due to a poor connection or corrosion.

I agree with sequel, something doesn't add up. Where are you located?

Good Luck, L.M.
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Old 11-06-2019, 11:50 AM   #43
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Kim57, you state that the voltage out of your ECU is 6.6 volts. I assume you're using a multi meter to determine that.
Rather than using your powered test light, why don't you use your multi meter to look for circuit continuity?
I'm wondering if the powered test light might be giving false positives. It could be showing continuity if only one end of the wire is connected.

If you connect the multi meter to each end of the wire it'll tell you if there's a break and if there isn't a break, it'll tell you if you have excessive resistance due to a poor connection or corrosion.
Actually it's reverse. Kinda of. The fact that he is using a test light through the wire is actually better. It gives an indication that the wire can hold current. When using an ohm meter, it cam give you 0 ohms even though the wire might not hold enough current. Example would be on a multi strand wire. If all but one wire is cut, the ohm meter will show 0 ohms as it uses very little current to check.

Ideally you'd use both. Run current through the wire and check for voltage drop with a DVOM. Not sure it's required here as current for a Hall effect sensor is pretty low.

The big wild card here to me is pin fitment with the connector ends and how Kim is testing. Other things that may be going on...is that 8v getting grounded somewhere to the vehicle speed sensor or the crank sensor.

Kim, if you were my neighbor, I'd be helping ya.
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Old 11-06-2019, 12:44 PM   #44
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Kim, if you were my neighbor, I'd be helping ya.
That's why I asked where he's located. If he's within reasonable driving distance I'd go see if I could help.

Good Luck, L.M.
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Old 11-07-2019, 09:07 AM
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Thanks for all the input guys.
Unfortunately I'm in So. Ca.
I'm going to start checking some of the other wires to see if any of them have a break.
Probably end up being something simple but a little frustrating right now.
Kim
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Old 11-07-2019, 09:55 AM   #46
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Where in So. Ca.? It's BIG....
There are view of us out here.
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Old 11-08-2019, 04:41 PM
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Where in So. Ca.? It's BIG....
There are view of us out here.
I'm in Corona.
It's in Riverside County.
Kim
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Old 11-09-2019, 02:13 PM   #48
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Started with the 4.0 Distributor until the diagnostic code. Got a new dis from AutoZone and had same problem. Was told AutoZone Dis was probably junk so got a reman from NAPA that had the same part number as the 2.5 so decided to use that one as that engine ran fine. Used a new cap and rotor in it.
No part of the 2.5 harness was used. Unplugged everything and left the harness intact on each engine as we pulled them.
All connections were made on the install of the 4.0.


CPS and 2.5 distributor.
Plugged the 2.5 coil in to see if that would eliminate the problem but it didn't so we are still using the 4.0 coil.
2.5 and 4.0 distributor have the same part number at NAPA.
Seems the only difference is the cap.
Rotor is also the same.

Kind of leaning toward a bad ECU but as this is the first time doing this maybe we missed something simple. Unfortunately he didn't hear the 4.0 run before he bought the donor vehicle.

Thanks for the help.
Kim
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Is a 4 cyl distributor actually supposed to work in a 6 cyl engine?

Good Luck, L.M.
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They have the same part number when you go to replace them.
Only difference is the cap.
Kim
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When I first started working on cars in 1960, all gasoline powered cars had points & condensers in the distributor. A 4 cyl distributor shaft would have a 4 lobe cam to open and close the points. A 6 cyl distributor shaft would have a 6 lobe cam to open and close the points.

With that in mind, I would have never considered attempting using a 4 cyl distributor in place of a 6 cyl distributor.
I looked on the NAPA and Rock Auto sites and indeed, the re-man distributors have the same part number. When you scroll down the NAPA page with the re-man 4 cyl distributor it states it's for a 6 cyl.
Both NAPA and Rock Auto have new OE distributors and they have different part numbers.

I don't dispute that a 4 cyl and a 6 cyl distributor can be interchanged because I just don't know enough about the innards of electronic distributors.
For peace of mind, I'd examine the area on each distributor shaft that activates the sensor. If they're the same, well, carry on. If they're different, be sure to reinstall the 6 cyl distributor.
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That's why I asked where he's located. If he's within reasonable driving distance I'd go see if I could help.

Good Luck, L.M.
The question about a 4 cyl distributor working in a 6 cyl motor has been bugging me. I decided to look a bit farther than part numbere.

Here's a couple pics of the distributor I took out of my 4.2 when I installed my HEI distributor.
If your 4 cylinder distributor doesn't have the 6 "teeth" or vanes that the pics show, I can't see how it can work in your 6 cylinder motor.

You can pull the cap & rotor of each distributor to look at the vanes and compare. The distributor in the pics is from a computer controlled carbureted motor. A Fuel injected motor might have a different style of distributor. I would still expect a 4 cylinder motor distributor to have 4 vanes or 4 similarly functioning devices and a 6 cylinder motor to have 6 of such devices.
In any case, if you still don't have your motor running, it's an easy thing to check.

Let us know what you find.

Good Luck, L.M.
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Old 11-09-2019, 04:45 PM   #49
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I've never seen a distributor for a 4 cylinder working in a 6 cylinder engine. It is impossible.
Look at the old stiles with breaker points, the shaft for a 4 cylinder has 4 lobes, for 6 cylinder it has 6 lobes and for a 8 cylinder it has 8 per revolution. Lobes or fins for a magnetic pickup coil need to match the number of cylinders,,,,,,,period.
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Old 11-10-2019, 09:54 AM
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The question about a 4 cyl distributor working in a 6 cyl motor has been bugging me. I decided to look a bit farther than part numbere.

Here's a couple pics of the distributor I took out of my 4.2 when I installed my HEI distributor.
If your 4 cylinder distributor doesn't have the 6 "teeth" or vanes that the pics show, I can't see how it can work in your 6 cylinder motor.

You can pull the cap & rotor of each distributor to look at the vanes and compare. The distributor in the pics is from a computer controlled carbureted motor. A Fuel injected motor might have a different style of distributor. I would still expect a 4 cylinder motor distributor to have 4 vanes or 4 similarly functioning devices and a 6 cylinder motor to have 6 of such devices.
In any case, if you still don't have your motor running, it's an easy thing to check.

Let us know what you find.

Good Luck, L.M.
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I've never seen a distributor for a 4 cylinder working in a 6 cylinder engine. It is impossible.
Look at the old stiles with breaker points, the shaft for a 4 cylinder has 4 lobes, for 6 cylinder it has 6 lobes and for a 8 cylinder it has 8 per revolution. Lobes or fins for a magnetic pickup coil need to match the number of cylinders,,,,,,,period.
Sounded weird to me also but they are the same inside.
Neither one has the normal pickups. They have a pulse ring.
Kim
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