doing 4.0 swap electrical problems need advice

[moosemeadows]

Hey I've got an 87 Bronco ll with a 93 Explorer 4.0 that someone started a swap and ran into some electrical issues. The previous owner installed the motor and harness and then had a small fire which melted a few of the wires.I"ve gotten it to turn over with the key and all my lights work but it seems like I'm not getting any power to computer or fuel relay and pumps. They don't click or run like my 89 Bronco ll. I should have paid my attention in Mr. Crandall's electrical class. Any thoughts ideas suggestions would be appreciated. I've read most of the stuff about doing the swap electrical wise but I'm just missing something. Looking forward to hearing your thoughts. Thanks in advance.

 

[RonD]

Welcome to TRS


How far did the swap go?

Did they do the whole electrical system in engine compartment, i.e. fuse/relay box?
Or just the engine harness.

The EEC relay, is a main component, it is in engine fuse box or on fender(brown base) it is activated when key is turned on.
When EEC relay closes it sends power from a 30 amp fuse(or fusible link) to EEC(computer), Coil/EDIS module, fuel injectors, and fuel pump relay(not fuel pump).

EEC relay is grounded locally, power from ignition switch causes it to close.

Fuel pump relay(green base) is not Grounded, it gets 12volts from EEC relay but won't close until Computer grounds it, once closed it passes power from another 30amp fuse(or fusible link) to the inertia switch and to the fuel pump(could be 2 pumps on 1987).

I would also unhook the alternator wiring, at the alternator end, and tape up the ends of the wire, until the rest is sorted.

Have a look here: http://www.therangerstation.com/tech_library/EDiagrams/index.htm

The 2.9l B2 wiring will be similar if it is being used.

4.0l 1991 should be the same if it was used.

 

[moosemeadows]

Thanks for the reply Ron.
It appears that they used the complete harness plus the engine harness. The distribution box is there full of fuses and 6 relays. The harness that got burned is what I'm thinking the harness that goes to the left side and hooks into the 87 stuff. I do know that the fuses are hot but relays not sure. Checking at computer I'm not finding any power but have it at the inertia switch. I'll go look at what you suggested and get back on later to see if you have any other thoughts. Thank you again.

 

[moosemeadows]

Ron the relays who asked about are laying with the 2.9 harness on the floor. I'd guess then I'm dealing with the 4.0 harness from the right side distribution box to the drivers side hooking into the 2.9 stuff there. I checked for juice at the ignition switch and have constant 12v in both yellow wires. I get 12v in the red/lt grn wire when I turn the switch as to start it. So as I see it I've got to get from there to the tan/blk coming from the PCM relay which when the switch is turned will close the fuel pump relay. Correct? It should also power up the coil and the ICM. Boy what a mess I've gotten myself into.

 

[RonD]

EEC(PCM) Relay and FP relay will be in the fuse box on '93, so '87 relay should be out on the floor.

There should be a layout diagram under the lid.

These numbers are from my 1994 Ranger diagrams
Pin 1 on the PCM should have power 24/7(keep alive power), this is from fuse #4(30amp), yellow wire
There is also another yellow wire from this fuse that goes to PCM relay, this is the power that goes out to PCM, Coil, EDIS, and fuel pump relay when PCM relay closes.

Yes, tan wire going to PCM relay should have power when key is on
Black wire is the ground
Yellow wire is from above 30amp fuse(should always show 12volts)
Red wire has 12volts when relay is closed, this wire is spliced many times, it feeds all 6 injectors, the coil, the Edis module, MAF sensor, EVAP system, fuel pump relay and pins 37 and 57 on the PCM.

Loads of red wires

 

[moosemeadows]

Back to checking out this new info. More questions later I'm sure. One just came to mind. Does the power distribution box come apart? It appears as though it might but before I break it apart I thought I'd ask. Thank you again.

 

[RonD]

It would have to but never tried to do it myself.

Problem for me is never taking something apart...........putting it back together is where it all goes bad for me

 

[moosemeadows]

Yes I do agree that taking something apart is always the easiest part of any job I've found that I'm not getting any power to the yellow wire at the computer so that's where I'm at now. Will try a little longer today get some sleep and pick up the attack tomorrow with some fresh eyes.

 

[RonD]

If on pin 1 then that would be the 24/7 "keep alive" power, PCM uses it to retain memory, like long term fuel trims, codes, IAC and TPS voltages.
Very little draw, it is similar to the power used by the radio to keep Pre-sets stored in memory.

Should come from same fuse as the PCM relays yellow wire power, so that fuse could be bad

 

[moosemeadows]

I have power at 37 & 57 but nothing at 1 I checked the fuse and it showed good but will try another in the am. I'm almost to the point of splitting the loom to check for a broken wire or running an overlay from distribution box to computer.I'll sleep on it tonight and formulate a plan in the am.

 

[RonD]

More diagrams here: http://www.justanswer.com/ford/1ju8k-93-ford-ranger-4-0l-automatic-running-fine.html

 

[trail B2]

When I put a 93 4.0 in my 86 B2 I had trouble with the steering column.I changed the dash but the fuel pump wouldn't work them I noticed The pink wire with a black stripe going up the 93 column Then I put the 93 column in the Bronco and everything started working.

 

[moosemeadows]

Ron thanks for the diagram and test procedures. I'll work on that today after I get some power to #1.
Trail B2 thank you for that thought as well. My Bronco looks very similar to yours with the larger tires. I maintained my original dash so far as it seems to work but without it running tough to know.
Thanks all for reading this and all your thoughts and insight. We'll get it figured out hopefully sooner than later.

 

[moosemeadows]

After another day of checking stuff I found the problem which as always is one of the first things I should have checked. When the guy installed the harness he plugged the connectors together w/o making sure the wires match on the other side. I want to thank you both for the help and your insight. So tomorrow will be another day working on my newest project.