'86 MJ 2.5L ECM....good?

[SoCalManche]

8 minutes ago, eaglescout526 said:

Yeah whether the relay is in the socket or not, we will still find the three that are hot. No worries about talking out loud, helps one to think.

So I got three batt voltage readings, but comparing my connector to the diagram, they would be 100_D1, 100_E1, and 100_E4, not 100_D4.

[eaglescout526]

I did say I didn't think it was that accurate right? Lol. Anyways that's good those have batt voltage so there's no resistance there. Lets see where number four is.

[SoCalManche]

7 minutes ago, eaglescout526 said:

I did say I didn't think it was that accurate right? Lol. Anyways that's good those have batt voltage so there's no resistance there. Lets see where number four is.

The only prong that hits batt voltage after jumper connects is 100_F4.

[eaglescout526]

Perfect! No resistance from the relay to the block. Hopefully meaning no more rooting around in the engine bay harness. Now let see what we get at the pump once you get it all back together. I'm not sure how possible it is but are you able to probe 100_F4 on the bulk head to the FP connector? If you can we should get an Ωhm reading on that.

[SoCalManche]

1 minute ago, eaglescout526 said:

I'm not sure how possible it is but are you able to probe 100_F4 on the bulk head to the FP connector? If you can we should get an Ωhm reading on that.

Are you meaning after I connect it back up and go probe it under the dash? 

[eaglescout526]

No sorry. It was an after thought of my prior statement. Probe it before you reconnect it. I want to see if theres any more resistance in the line. I would probe it from the engine bay and see how far you can bring the FP connector to you.

[SoCalManche]

Just now, eaglescout526 said:

No sorry. It was an after thought of my prior statement. Probe it before you reconnect it. I want to see if theres any more resistance in the line. I would probe it from the engine bay and see how far you can bring the FP connector to you.

Yeah, sorry. I understood after I posted. It seems to be a hair over 5 ohms.

[eaglescout526]

Doesn't sound like a lot of resistance. Course be better if we has none but that resistance could be anywhere and we aren't looking to tear up the interior and fuse block just to find it. Alright lets slap her back together.

[SoCalManche]

Just now, eaglescout526 said:

Doesn't sound like a lot of resistance. Course be better if we has none but that resistance could be anywhere and we aren't looking to tear up the interior and fuse block just to find it. Alright lets slap her back together.

Interior panels have already been torn up from last year when I tried hunting down the issue initially. 

 

Well, at least the panels near the driver's side door all the way to where the wires dump under the cab to the FP connector.

[eaglescout526]

Yeah but I don't think the problem will lie in the wiring unless the wiring under the cab got the insulation chewed up from road debris and corroded any exposed wire or theres some resistance in the bulkhead plug.

[SoCalManche]

7 minutes ago, eaglescout526 said:

Yeah but I don't think the problem will lie in the wiring unless the wiring under the cab got the insulation chewed up from road debris and corroded any exposed wire or theres some resistance in the bulkhead plug.

Well what would be another solid test inside the cab to track down an electrical gremlin for the FP?

[eaglescout526]

You know, I am not sure. According to the schematic there is only one connector between the pump and C100 and that's the three prong plug. So the only thing I can think of would be to examine the pink with tracer wire and see if theres any breaks or rips in the insulation that could've caused corrosion. My other idea is to plug C100 back in and check the voltage but I believe you have to screw the bolt back in just to get the two halves to seat properly.

[SoCalManche]

1 minute ago, eaglescout526 said:

You know, I am not sure. According to the schematic there is only one connector between the pump and C100 and that's the three prong plug. So the only thing I can think of would be to examine the pink with tracer wire and see if theres any breaks or rips in the insulation that could've caused corrosion. My other idea is to plug C100 back in and check the voltage but I believe you have to screw the bolt back in just to get the two halves to seat properly.

Screwing it back in is a piece of cake. I bought flexible extensions, and damn do they make life easy. I am down for anything and everything when it comes to the MJ.

[eaglescout526]

Well theres a couple options for ya. Otherwise I don't have any other testing ideas.

[SoCalManche]

2 minutes ago, eaglescout526 said:

Well theres a couple options for ya. Otherwise I don't have any other testing ideas.

I will do both. When I check voltage, do you mean check at the FP connector?

[eaglescout526]

Yes, because we know there is straight batt voltage from the relay to C100. So lets see if it carries on.

[JustEmptyEveryPocket]

And remember that if your multimeter tells you 12 VDC, you aren't done yet. Make sure it can light your testlight nice and bright. That way you know it can also carry the load.

 

I might have been bit by this before . . . Sorry to be extra cautious.

[SoCalManche]

12 minutes ago, eaglescout526 said:

So the only thing I can think of would be to examine the pink with tracer wire and see if theres any breaks or rips in the insulation that could've caused corrosion.

Are you sure pink w/ tracer? It doesn't dip down into the next connector. Maybe orange w/ tracer.

[SoCalManche]

2 minutes ago, JustEmptyEveryPocket said:

And remember that if your multimeter tells you 12 VDC, you aren't done yet. Make sure it can light your testlight nice and bright. That way you know it can also carry the load.

 

I might have been bit by this before . . . Sorry to be extra cautious.

Hey man, extra caution is good. I always like to double/triple check things to solidify my findings, so I appreciate the tip. 

[eaglescout526]

 

Says pink with tracer. Unless yours is a late model '86 and the wiring was changed which is kinda what I'm thinking is going on here.

[SoCalManche]

16 minutes ago, eaglescout526 said:

 

Says pink with tracer. Unless yours is a late model '86 and the wiring was changed which is kinda what I'm thinking is going on here.

Ah, I see now. So the late-model '86 is the true unicorn. Haha!

[SoCalManche]

https://drive.google.com/open?id=15PUsED9JeYRVHWpinhYtJxcXIS977iGB

[eaglescout526]

So probably the thick orange one. One of those pink wires is for the dome lamps and the other for the crago lamp. I can go look at the '87 electrical manual and see if they moved over to orange wire which they probably did. Wonder why they chose orange to go to pink for the FP.

[SoCalManche]

6 minutes ago, eaglescout526 said:

So probably the thick orange one. One of those pink wires is for the dome lamps and the other for the crago lamp. I can go look at the '87 electrical manual and see if they moved over to orange wire which they probably did. Wonder why they chose orange to go to pink for the FP.

Yeah, orange wire looks good. All the wires in the cab look pristine, at least where I can see them. I haven't gone up under the dash yet. 

 

I can disconnect C_200 and test it, yeah?

[eaglescout526]

Yep you can.