Well, turns out all the wire diagrams I have are completely different for the PCM/TCM connection. I need to get my hands on a '94 Bighorn 3.1 diesel wiring diagram. If anyone has that, please let me know. I have a '95 petrol diagram, a late '80s 2.8 diagram and a late '90s-early 2000s set of diagrams and none match the inputs to the PCM I have. I could gamble and assume colors that match are what the diagrams I have say, but I'm not too confident.

What i'm looking for are indicators of what all the wires that are not direct connections from the engine to PCM are. I also need to know what the wires are from the speedo/guage cluster.

If anyone has any suggestions, let me know. For now, I'm going to isolate the wires from the engine and transmission and match them to the PCM. That'll weed out 80% of the wires and I'll just have to figure out the remaining few.

Paul

I've been plugging away at my wiring situation. Does anyone know of a wiring diagram for a '94 bighorn? I'd be happy to buy Isuzu shop manuals, but I haven't been able to find any for that model year.

Where I'm at is I've removed the portion of the harness that connects my two engine plugs, three transmission plugs and the PCM/TCM (tramsmission computer). Some of the wires go directly between the engine/tramsission an the PCM, those I don't have to worry about. My concern is primarily the PCM wires that don't go to the transmission/engine. I'm sure at least one is ground and another is 12v, but the other 8 or so are unknown to me. Some would go to the winter/power switch, others to indicator lights for those mode, I'm not sure which though. The other wires are completely unknown to me. The 'unknown' engine wires are a little less of a concern, oil press, temp, glow plugs, etc. Those shouldn't be too hard to figure out by tracing them to their source.

I have looked at wiring diagrams for other years that I've sourced, some wire colors appear to match up to what I need to connect, but others are different colors between what I have and what my wiring diagrams for other years indicate.

I'm still cataloging what I have and will post the colors when I have them all mapped out.

Thanks!
Paul

Try This link. page 3 for complete manual.

http://www.isuzu.spottedhaggis.com/...at_view&gid=13&Itemid=33

Thanks for the link. It looks like that's the '95 owners manual. I do have copies of the '95 shop manual that hasn't clarified things too much. Between that and the 1998-2002 shop manual that is on that site as well, the wire colors don't match exactly to what I have, but some do. I'm going to start a new thread on this topic...

Paul

I happy to see some other people have done this sort of conversion.
This summer I plan to start work on putting a 2.8td engine from a mid 90's bighorn/Mu into my 98 amigo.
My biggest fears involve the differences in the motor mount points on the frame going from 1st gen Mu/Amigo to 2nd gen.
The 2.8 has no ECU and I want to stick with a 5spd, so i think my biggest electrical challenge will be making the speedo and tach work (at all, much rather well). I can make a module to trigger the stock tach off of an optical sensor setup, ive done quite a bit of reading about this. The speedometer, i may have to do something aftermarket, or use a GPS.

I plan to set it up with a front mount intercooler, so i can retain the stock hood. Plumbing this will be a chore, since the stock pipes are aimed right at each other where the stock top mount goes. Id like to mod the engine lightly, make a good amount of torque, and eventually start making my own biodiesel, as it doesnt sound like the fuel mileage with even the 4j engines is all that awe inspiring.

Oh, and I also have to put a front axle and front spindles in my amigo, to make it 4wd <img src="/forums/images/graemlins/rolleyes.gif" alt="" />

The first thing on my list is to rebuild the 2.2l gas engine so i can drive the amigo while i sell my other vehicles to pay for the engine. <img src="/forums/images/graemlins/scared.gif" alt="" />

<img src="/forums/images/graemlins/confused.gif" alt="" /> one question ive had all along in planning this out is do i need some sort of lift pump to get the fuel from the tank to the injection pump? When i was looking into putting a VW TDI in my suzuki sidekick, it seemed that they were using the stock in-tank gasoline pump to serve this purpose, but those of you working on isuzus have not done this.

thanks

Sounds like quite a project. You may want to consider a vehicle that doesn't need quite as much modification to begin with (at least a 4WD Amigo if that is your goal) so as not to get bogged down. We may make it look easy by posting our progress, but it's many hours spent trying to make things work; the easier you can make it on yourself, the better.

You don't need a lift pump for the 4JB1 engine, the injector pump will draw from the tank without assistance.

So, I've been plodding along with this. I had stalled with the transmission wiring and race season has taken from my time and focus on this. I'm finally at the point where I'm going to try to start the thing. Still lots of little details to take care of, but my goal is to at least start it and finish that milestone. I'll keep you all posted...

Paul

So, I'm in need of some troubleshooting help now. I'm trying to start the motor and no luck so far. I primed the fuel system all the way up to the fuel filter. I'm running 12v to the fuel solenoid/shut off that's at the back of the injector pump (I can hear it click when I put voltage to it). Then I'm cranking the thing over. I cycled it for maybe 15-20 rotations of the engine. No fire.

It's mechanical injection, so I would assume that all I need is to open the fuel cut off solenoid by applying 12v and then crank it over...

The fuel system was dry prior to doing this, so maybe it will take longer to draw fuel from the filter to the injection pump. Maybe I just didn't try long enough.

I did replace the timing belt prior to this, so there's a chance I messed something up there, but I was very careful to follow the instructions. I believe that is all good, but a point to consider.

I did not use the glow plugs at all. It's about 75 degrees F out, so I would assume neglecting them would be ok, at least to get it started.

I didn't try 'opening the throttle' at all. I suppose that's an option, seems like it shouldn't be necessary though.

Thoughts or suggestions?

Thanks!
Paul

I don't have specific knowledge of the Isuzu diesel, but I do have some experience with other diesels, specifically marine diesels.

Did you bleed the injectors? If not, a single air bubble can stop the fuel flow to the cylinders.

Paul-

Sounds like you need to bleed the injectors. Just crack the lines at the injectors and crank until you get fuel squirting. With power to the fuel solinoid of course. Make sure not to overheat the starter as sometimes it can take a bit of cranking if they are stubborn.

You don't need the glowplugs. I disabled mine once we hit about mid 40's in the morning and it starts with just a tap of the key and almost no smoke. It starts right up in the 20's without them too, but the blue smoke was a little excessive.

On a side note as I haven't posted in a while, I have almost 4k on mine now and I'm loving it. Been averaging 32 mpg with my foot into it everywhere I go.

Good Luck