3.4 swap into 1985 Jeep Cherokee questions?

[ssterlingb]

The injectors have 12+ all the time the ignition is on from the two pink wires. The PCM controls the ground for the injectors, so if they are not pulsing gas, the PCM is not wanting to run the engine.
We just need to figure out why.
At this point, all we need to look at is inputs to the PCM to determine why it does not want to run the engine.
The engine control module (PCM) controls the fuel pump, by way of the oil pressure switch & other safeties, the ignition control module (ICM), and the injectors. You HAVE to get the PCM to work these, NO EXCEPTIONS, otherwise the engine will not run safely, if at all.
I will get some images of the pages that might help from the service manuals tomorrow & send to you.

[ssterlingb]

There is a two wire connector from the ICM that is a blk/wht wire to ground & # 239 pink to a 10 amp fuse on the ignition source for power.
The Pink wire comes from the fuse and splits to the ICM and the camshaft position sensor.
This supplies power for the ICM.

[cardana24]

Pins B14 & B15 on the PCM are the keep alive memory, both orange wires connected together to a 10 amp fuse and then to a fusible link on the junction block.

I think I have both sets of wires hooked up the way you are describing. I don't have the Orange wires fused or hooked to a fuseable link, I just have them running straight on 12V all the time. Is that a problem? I will add a fuse and fuseable link when I get it running, but right now I just need to get it going, then I can fix all of that.

Why would my injectors not be firing? I just checked my plugs again and they have not gas at all on them. I have pluged in the factory harness to the injector harness and I have run the two pink wires to the ignition wire on the jeep. This is not make since to me at this point.

[ssterlingb]

Pins B14 & B15 on the PCM are the keep alive memory, both orange wires connected together to a 10 amp fuse and then to a fusible link on the junction block.

[ssterlingb]

The two pink wires show to go to two 7.5 amp fuses connected to the ignition source.
They are # 639 & 839. They feed the injectors on one side & the other side goes to the PCM, so evidently the PCM is the ground pulse for the injectors.

[cardana24]

Another thing to consider too...are we sure that the two pink wires in that black/grey harness should go to switched 12V...they are not to be grounded are they?

Also, which wire/wires are the grounds for the injectors? I know on my maxima I had similar starting issues when the injectors did not have a good ground.

[ssterlingb]

Okay, I have the chart in front of me. I wish I had some way to scan & send to you, but I'll try to explain if I can.
This is a couple of pages in the Factory Service Manual.

1. A MIL (Service Engine Soon) "ON" is a basic test to determine if there is a 12 volt supply and ignition 12 volts to the PCM. No data may be due to a PCM problem. The engine will not start without reference pulses and therefore the Tech 1 scan tool should display RPM (reference) during crank. If RPM is erratic it is possible that the reluctor wheel on the crankshaft is damaged.
2. For the first two seconds with ignition "ON," or whenever reference pulses are being received, the scan tool should indicate fuel pump circuit voltage (8 to 12 volts).
3. Because the electronic ignition control system uses two plugs and wires to complete the circuit of each coil, the companion spark plug lead should be connected to a good ground. If RPM was indicated during crank, the electronic ignition control module is receiving a crank signal, but no spark at this test indicates the electronic ignition control module is not triggering the coils.

The rest of it refers to the test determining if there is B+ at the injectores, or if the ignition control module is not triggering, or if the PCM is at fault.
There is a wiring diagram for the engine to PCM, and a test chart to determine the problem. I don't know what info you might need. I can probable find a scanner tomorrow & send to you if you need.

[cardana24]

Just a thought, have you installed a VATS module yet?

yes I have. the red LED lights up when I turn the ignition on and according to baker electronix, that is what it is supposed to do. Also if it were VATS related I have read that it would run for about 2-3 seconds then turn off.

Okay, I am still not making progress. Still turning over but not even trying to fire up. I have checked my plugs several times and they don't smell like gas at all...with the amount of cranking I have done with out the engine firing up the plugs should be soaked, and probably fouled. So that leads me to believe my injectors are still not firing. I have run fused wires from my ignition signal under the hood to the two pink wires that go into the Grey/Black harness...and I am still not getting anything. How should my wires be run to get my injectors to fire? I am going to go buy noid lights now just to confirm what I know to be true. I could understand if an injector was colgged but not all 6. Please help me out.

Also I hooked up the orange wire to a constant 12V source, and I have grounded the Grey and Black wires on the 3 pin black connector.

*edit* I also fixed my fuel pump wiring after I hooked up the orange wire, it is not running correct and is controled by the ecm.

Also I have wire B3 (ignition feed) going to my hot switched 12V lead in the jeep. Can some one varify this is correct. If not which wire should I have reading switched power ignition?

[ssterlingb]

Just a thought, have you installed a VATS module yet?

[Canyonero]

I absolve myself of any engine fires relating to this project.

[cardana24]

Umm, yeah!



Do you still not have these wires hooked up? I'd suggest hooking them up.

I have the PCM ground wire hooked up but not the two orange wires. I do not have the two orange wires hooked up though. I'll hook those up to the battery.

As for the fuel pump I had it hooked up to the ecm but that was not switching it on, it could be because I did not have the orange wires hooked up? I got switchable power from the ignition because the ecm wire was not turning the pump on.

ALso that is the reason I hooked up the pink wires for the fuel injectors the way I did. When I hooked them up from the ignition to the ecm pink wires the current was not getting to the injector harness, so I changed the wiring so that I was pulling power straight off of the ignition wire on the jeep and going straight to the pink wires at the injector harness...this gave me 12V at the pin locations.

[Canyonero]

Still no go. I ran a wire from my ignition wire to the to pink wires just before the plug into the injector harness by the fuel rail...is that correct? I am getting current in them when I turn the ign on. Of all of the wires that I posted not being hooked up I have only hooked up the one that says it goes to the ignition, I ran that to the positive ignition wire on my jeep, and now I have hooked up the two pink wires from the ignition wire on the jeep to the injector plug...other than those three wires the rest are still just hanging out.

Ehhhh? You don't need to mess with anything near the sub-harness. You just needed to clip the pink wires out of the Black and Grey connector we were just talking about. Put a fuse holder w/ 10-amp on each of those, connected to an ignition switched circuit.

I went through and re did all of the pins that were marked as "ECM Ground" there were four of them, they are all running to an 8gauge wire now which is bolted to the firewall under the hood.

Fine... 8ga. is overkill, but fine.

In Canyanaro's wiring instructions there are three wires that say they go to ignition module Connector 1, 2, and 3. Do I need to do something with that?

Those wires go between the ECU and the ignition module. You shouldn't need to mess with those. The ECU needs constant (keep-alive) and ignition switched power. The ECU will provide power to the other sensors, etc, that need power. With the exception of the fuel injectors which have their own fuse per bank. And the fuel pump, which should be fused on your kit.

What you should mainly be concerned with in my harness instructions is locating and correctly splicing the wires in the Tails/Dash Connection section.

Also I have cut the fuel pump relay off of the ecm since I am using a universial relay kit for that. I am picking up the switchable power off of the ignition wire on the jeep as well, I don't think this would cause a problem but you can let me know other wise. i have also tried my other ecm and I am still not getting anything.

When I leave the key in the on position the fuel pump is very audible while in the tank and I am getting a hissing noise coming from the engine bay. Every time I check at the schrader vavle on the fuel rail I have plenty of fuel shoot out (The gauge I have cannot be put on this valve).

You want the fuel pump controlled from the ECU, it will prime the pump for a few seconds to pressurize the system when you turn the ign on. There is no need for it to run constantly when the engine isn't running, you'll just wear out the pump and drain your battery. It's also a way to tell if your ECU is working at all.

Do I need to run some sort of power wire for the ecm? What gives? I could really use some help.

Yes, you will need the orange wires bszopi pointed out connected to the battery. I assumed you'd already done that.

My harness (and the original Trooper wiring) used a fusible link to protect the keep-alive circuit. I don't know much about those, why you'd use one instead of a conventional fuse. I just hooked it up. Perhaps someone else can explain that one.

[bszopi]

Do I need to run some sort of power wire for the ecm? What gives? I could really use some help.

Umm, yeah!

4 pin Black harness
Grey- Nothing (Caynonaro said it was 5V ref)
Orange- B14,B15 Battery (keep alive memory)
Black/White- PCM ground
Purple- Ring terminal in harness

Do you still not have these wires hooked up? I'd suggest hooking them up.

[cardana24]

Still no go. I ran a wire from my ignition wire to the to pink wires just before the plug into the injector harness by the fuel rail...is that correct? I am getting current in them when I turn the ign on. Of all of the wires that I posted not being hooked up I have only hooked up the one that says it goes to the ignition, I ran that to the positive ignition wire on my jeep, and now I have hooked up the two pink wires from the ignition wire on the jeep to the injector plug...other than those three wires the rest are still just hanging out.

I went through and re did all of the pins that were marked as "ECM Ground" there were four of them, they are all running to an 8gauge wire now which is bolted to the firewall under the hood.

In Canyanaro's wiring instructions there are three wires that say they go to ignition module Connector 1, 2, and 3. Do I need to do something with that? Also I have cut the fuel pump relay off of the ecm since I am using a universial relay kit for that. I am picking up the switchable power off of the ignition wire on the jeep as well, I don't think this would cause a problem but you can let me know other wise. i have also tried my other ecm and I am still not getting anything.

When I leave the key in the on position the fuel pump is very audible while in the tank and I am getting a hissing noise coming from the engine bay. Every time I check at the schrader vavle on the fuel rail I have plenty of fuel shoot out (The gauge I have cannot be put on this valve).

Do I need to run some sort of power wire for the ecm? What gives? I could really use some help.

[Canyonero]

My gut tells me that's right. But sometimes my gut doesn't know what the hell it's talking about. But I do know that the two injector banks are fused independently from each other and the ECU.

If you do the tests I described, that should verify it:
If you don't have the sub-harness connected, you won't have continuity between those two pink wires and C12-16,32. If it's hooked up right, you will have 12v at the individual injector connectors. Make sense? I don't always make sense. Hope someone chimes in if I'm way off...

You need a noid light to test for the trigger pulse, but I think you'll be fine.