Duramax Diesel Conversions

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You can also read more about Lil Red here on TDP.

Jim

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In your conversion truck, how did you get the climate controls and radio to work, I know that your conversion guide mentions that it includes information to produce a running and drivable truck. So, are there any manuals or wiring diagrams for those kind of things in the truck? Also what kind of unforeseen problems further down the road have you run into? Any electrical or drive train problems or other little things? Any help is very appreciated thank you-Robert

I installed the complete under dash/inside cab wiring harness, fuse block, and electrical junction blocks matching the engine/trans package. I also installed a matching dash. This allowed me to use the matching audio system, light switch, pushbutton 4WD switch and instrument panel gauge cluster. I retained the original 1989 control panel for the HVAC system by interfacing it with the new harness. This is covered in the Conversion Guide (HVAC system).

No problems with the drivetrain have come up, except that if doing it again, I would install a matching model year steering column, which would simplify the conversion. The Guide shows how to retain the original steering column and get the cruise, turn, horn and wiper system integrated into the new electrical system.

Jim

For this conversion, how much would the approximate cost be? I've read all the articles I can find on the conversion you did with the '89 however I can’t find a build cost. I'm looking to do it to my 1996 and was wondering about an approximate build cost to just get it running and drivable. Thank you -Robert

Assuming you did all the work, the total cost would depend on what you pay for a conversion package. I've heard of packages going for $5k to $12k. Many almost-new low mileage salvage trucks go for somewhere in the $7500 range, but you'd need a salvage license to bid on insurance vehicles. Ebay can also be a good source for engines and parts.

Jim

You mentioned a conversion kit, aside from taking the parts out if a salvage truck what do you mean?
Thank you Robert

I referred to a conversion parts package that was assembled from a salvage truck. A package will contain the complete engine/transmission, all related wiring harnesses, computer modules, fuse blocks, electrical center, intercooler/hoses, radiator, steering column, etc.

There have been a few "packages" sold on eBay. I urge people to buy a complete package or a complete salvage truck. The little bits & pieces can really run the cost up if you have to buy them over the counter.

Jim

[Margo_325]

Im doing conversion on a 1995 Suburban. Donor car is 2001 Silverado. I have the book "Duramax 6600 Conversions&Repower Projects"

My Suburban does not have an HVAC like in the book, I took all the wiring out behind dashboard (I want to keep the old dashboard), that included all heater wiring as well. Do I just have to compare two car wiring diagrams and search for right wires to connect to heater plugs?
I only left the wires, that came out from drivers door and went behind dashboard to passenger door. How did you get your power windows and central locking to work, I didn´t find anything from the book, how to connect them.

Margo, Estonia

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Im doing conversion on a 1995 Suburban. Donor car is 2001 Silverado. I have the book "Duramax 6600 Conversions&Repower Projects"

My Suburban does not have an HVAC like in the book, I took all the wiring out behind dashboard (I want to keep the old dashboard), that included all heater wiring as well. Do I just have to compare two car wiring diagrams and search for right wires to connect to heater plugs?
I only left the wires, that came out from drivers door and went behind dashboard to passenger door. How did you get your power windows and central locking to work, I didn´t find anything from the book, how to connect them.

Margo, Estonia

Your complete HVAC system & control panel should work just like mine does, meaning it'll operate as a standalone system. You'll just need to tap into DMax HVAC under-dash wiring for power/ground/AC clutch engage. I recommend using the Dmax HVAC power and lighting circuits so the correct the fuses are being used. The 88-94 diagram in the book can be used as a guide for your 95 system, but you will likely need the 95 wiring diagram to double-check it.

As was mentioned by THEFERMANATOR, the ECM will be looking for the Dmax HVAC controller. I didn't need to delete that function in the ECM using EFI-Live, but it wouldn't hurt.

If you want to maintain 4-wheel ABS, I would transfer the Dmax truck's ABS controller and related hardware to the Suburban.

And by the way, I consider the Dmax instrument panel essential for the best conversion (the gauges are right and you'll have the DIC).

Jim

[Margo_325]

I did put the Dmax instrument panel cluster in a Suburbans dashboard and fabricated a plastic cover around it. Also I did put a Dmax dip switch, that fitted almost perfectly. So for the HVAC I need just to connect 3 wires to make it work correctly (power, ground, A/C Clutch)? Unfortunately, I dont have Suburban wiring diagram, only the Silverados one.

[More Power]

The pickup wiring diagrams should be virtually identical to the Suburbans.

The HVAC package under the dash should have its own wiring harness - that connects to the HVAC control panel and the vehicle's original under-dash harness.

I connected the original 1989 HVAC harness to the new Dmax harness connections for power/ground and Ac clutch engage. Works great.

Jim

[GordonMarks]

Well, 1st off, mine was an OBD II & you guys, fortunately are dealing w/OBD I.
My Opinion:
You need to get the GM FACTORY MANUALS!! It has all of the wiring diagrams.
The A/C..As I recall, youall are on the right track-LOOK AT THE "a/c Request" wire.
The 95-99(2000 for some) A/C wiring is the same. The control head is a computer.
I'm not sure how you can get the 95 dash to work with the 01(DMAX) since all of the inputs(outputs?) are different & changed again several times.
I used the 01(actually 01-03 I think)DMAX dash & it is usable/fitable(if that's a word)
I need to read the posts again.......

[GordonMarks]

OH, the 95-99 A/C system controls are DEFINITELY different! They changed the controls & the dash. The basic system(box) is the same but the control head is alltogether different as is the wiring.
The ducts are better too. The air flow/cooling(for those down here)is much better on the 95-99's but not as good as the later 2000's +.

[Margo_325]

Thanks, but I already subscribed as a member to alldata myself. Now I got the heater working (need to find the A/C engage wire, but I have some small problems left still. First, how should the coolant circle go through the heater? I have 3 pipe endings coming out from firewall, one I know is A/C pipeline, the other two are for the heater inside.
http://stuff.e30club.org/images/suburban/hoses.JPG
Problably the bigger one is intake hose and smaller outlet? Duramax has two exactly same size hoses, one is coming from the waterpump or near there and the other one is coming from that big hose, that goes to the radiator right side. Correct me, if Im wrong, but then the hot water comes from the lower hose, that goes to the radiator, goes through heater radiator and then goes back to the water pump? Of course, then it gets warm in car, when thermostat valve opens. And also I have A/C hose problems, if someone could explain me the schema, how I can fit them so my A/C fluid circle will be right. If someone can explain me, how I should fit those hoses, I´d be very grateful.

Edited:
Still one more little problem: I have that kind of wiper plug, that does not fit to the suburbans wiper motor, and it has 6 wires, but suburban has only 5, so any ideas? The Duramax wiper motor is different and cannot be mounted on the suburban body.
Picture of my plug:
http://stuff.e30club.org/images/suburban/wiperplug.JPG

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Thanks, but I already subscribed as a member to alldata myself. Now I got the heater working (need to find the A/C engage wire, but I have some small problems left still. First, how should the coolant circle go through the heater? I have 3 pipe endings coming out from firewall, one I know is A/C pipeline, the other two are for the heater inside.
http://stuff.e30club.org/images/suburban/hoses.JPG
Problably the bigger one is intake hose and smaller outlet? Duramax has two exactly same size hoses, one is coming from the waterpump or near there and the other one is coming from that big hose, that goes to the radiator right side. Correct me, if Im wrong, but then the hot water comes from the lower hose, that goes to the radiator, goes through heater radiator and then goes back to the water pump? Of course, then it gets warm in car, when thermostat valve opens. And also I have A/C hose problems, if someone could explain me the schema, how I can fit them so my A/C fluid circle will be right. If someone can explain me, how I should fit those hoses, I´d be very grateful.

Edited:
Still one more little problem: I have that kind of wiper plug, that does not fit to the suburbans wiper motor, and it has 6 wires, but suburban has only 5, so any ideas? The Duramax wiper motor is different and cannot be mounted on the suburban body.
Picture of my plug:
http://stuff.e30club.org/images/suburban/wiperplug.JPG

In my 1989 Duramax conversion, the heater pipe closest to the engine on the truck's firewall connects to the upper heater supply hose coming from the Duramax engine. I bought a new silicone hose made for a 6.5 engined truck to sweep up and connect to the Duramax heater hose supply line.

Wipers... I used a new complete in-cab wiring harness, and I maintained the original steering column. Using the 2001 harness wires used for the wipers, I made the connections between the wiper control stalk and the wiper motor (using the original electrical connector) using the 1993 wiring diagram. If your vehicle is newer and you're using the original steering column, use the matching wiring diagram to know what function each wiring connection is supposed to operate.

Are you using the original steering column or a column matching your engine package (which is what I recommend for an easier install)?

Jim

[Margo_325]

To Jim: I´m using a Duramax steering column as well. Theres minor problems fitting it, because the lower bracket does not fit and needs to be welded to another place. Same with the shifting cable bracket on the steering column, because Im using my original Suburban shifting cable (it is tight)

To THEFERMANATOR: Could you explain it to me (a simple schema or something), because I have zero knowledges about relays. I know, that I have one wire, what turns on the light in the A/C button, if I give there "+" from battery.

[THEFERMANATOR]

The A/C control head in the 95-99 SUB's output's a 12V+ signal to the A/C system to request the compressor to come on. The 01 DMAX uses a ground signal from the controller to the ECM to trigger the A/C. So you would need to use a relay that is turned on by the 95 control head that would ground the A/C request signal to the ECM. And the A/C light in the control head is turned on by a controller inside of the A/C control head itself. Also the power for the blower motor in the HVAC comes through the origanal underhood harness that ran behind the engine and came down underneath the old coolant bottle. This is the same harness that origanally had all of the ECM wiring in it.

[Margo_325]

Ok, I think I try to do so. Another sad surprise came up. I connected all wires, that is needed to run the engine, so I can start wiring power windows, electric seats etc. I turned the ignition on and only this yellow "Check engine" and glow plug lights came to life. As I don't have any oil in the engine, I didn't try to start it yet, just tried, if starter works and it did. Of course, I don't have a key, the lock cylinder is taken out and I have a big screwdriver as a key, but still, I suppose, Passlock will not disable any lights like battery or oil in dashboard? No gauges were working either. Its weird, because I haven't done any wiring myself, besides these red wires on the picture (they fit anywhere, so I did just put them somewhere)

And also thereare 2 plugs left over under hood:
(comes out from that red box)

and two ones under dash: (yellow one seems to be like airbag plug, but that already connected on the steering column)

Any ideas, where I should start tomorrow?

[More Power]

No gauges were working either.

Several of the gauges are operated by the vehicle ECM via digital data - not directly by engine sensors. So, the ECM has to be installed for all of the gauges to work as they should.

I would expect some modification of the steering column mounts would need to be done to get the newer style column installed. That is all pretty basic, and having the new correct column would make the overall installation a lot simpler. Personally, I'd get the correct Allison shift cable, and not try to reuse the original Suburban shift cable.

If someone else started the electrical/electronic installation, and didn't document everything, you're in for some late nights tracing wires and figuring out what was done. In my conversion, I documented everything, and kept detailed records, both to help me in the future if I need to troubleshoot a problem and to help any future owner should I sell this truck.

One aspect of the conversion I kept firmly in mind during the process was to keep the conversion as "factory" as possible. Any deviations from this are thoroughly documented (like the HVAC, wipers, etc). This would allow a GM dealer technician to troubleshoot this D/A conversion just like he would a stock 2001/2002 D/A truck. Nearly all circuits, fuse blocks, individual fuses, harnesses and all electrical layout are almost exactly as they are in the 2001/2002 trucks. The conversion guide was written from that perspective. One reason for doing this was because no one else had completed a GM truck conversion at that point in time (in 2003/2004). If I needed help from the local GM dealer, I wanted them to be able to use their routine troubleshooting resources to help. I knew that custom wiring, custom ECM/TCM, mismatched wiring and mismatched circuits would make it nearly impossible for another person to help. And lastly, I wanted this conversion to look as neat and professional as possible.

Jim

[Margo_325]

Ok, after hours searching, I managed to get my instrument clusters working. It was some grounds, that werent connected. Of course, now it works when ever wants, so some more problems to search for. Now I´m stuck again, because of the fuel pump. I have the suburbans fuel pump, but no duramax one. Where should it be located? I checked the fuel tank, but there was only the level indicator and in the tank there were going only 2 wires (purple and black, probably for level indicator). I have alldata opened, and it shows, that both cars have same colour fuel pump wires (grey and black), but I cant find any available connector in my duramax harness. I used all duramax harness (C3 and C4) under my car. Of course, one opportunity is to make new harness, going from fuel pump relay to the fuel pump, but why to invent something, that should already be there? The alldata shows this diagram:
http://stuff.e30club.org/images/subu...el_control.gif

Also a quick question, how the tail lights should work? There is going 4 wires in, but theres 3 bulbs, each with two strands (or how it is called in english). I sorted out the right wires from Duramax harness, but now idea, how to connect them with suburban lights.

[ToddMeister]

Margo,

The duramax does not use a fuel pump in the tank, the CP3 pulls fuel itself from the tank thru the fuel filter and up to the pump.

Some folks add lift pumps on the frame rail to help the CP3 get more fuel. They will run the pump thru an oil pressure switch so the fuel pump turns off when the engine is not running.

[Margo_325]

Okay, now I just connected the fuel lines, but as suburban has smaller pipe coming out from fuel tank, does it affect the engine work? Today I filled engine with oil and tried to start it with my "screwdriver key" and it actually started for a second. Of course, Passlock then interrupted. What I noticed, that if I turn ignition on, then on the info panel in the dashboard, it says: "Driver 1 - Odometer: 116000 - Low Fuel, Service 4WD, and then it stays at odometer (you can change by hourmeter, business and so on from the button there). But in the book, I saw, that Jim had all gears marked up there (P, R, N, D, 3, 2, 1), if the ignition was on. Well, Jim had little bit different instrument panel as well, but I still think, that it should show it. I got the tail lights working after some hours (in Europe you have to have amber indicator lights, so thats way I was confused).

PS! My headlights are acting weird. When I turn the ignition on, then theres low beam, if I change to high beam, the low beam goes off, actually they both should be on...

[Margo_325]

Now I started connecting inside wires and bad thing is, that my junction block does not match with Jim´s one and if I checked the ALLDATA, then that one there didnt match with mine nor Jim´s.
http://stuff.e30club.org/images/suburban/juncblock.JPG
So I just have to pull out all fuses and put them in one-by-one to see, where I need to connect the right wire or someone has a better solution?

[More Power]

I bought the full set of GM manuals and the separate electrical diagram book for the model year of the engine package I used. In these books was an illustration and pinout descriptions for the junction block I used. If buying the books isn't a possibility, I'd visit a a local dealership and try to get a printout from them for your junction block.

By the way, the separate electrical diagram book isn't strictly necessary because the individual diagrams can be found scattered throughout the service manual book set. Being scattered makes it more time consuming to get all of the information, so I found it better to have all of the diagrams in one book. I recommend getting the GM electrical diagram book matching the model year of your engine package.

By the way, please don't post scans of diagrams or other copyrighted material from AllData or any other source.

Jim

[Margo_325]

As Im building a car in Norway, then in this country, it isnt possible to buy this book, they just dont sell it. Although I purchased all possible versions in alldata, that my donor car could be. It turned out, its a 2003 year model. I noticed, that every year has its own junction block under the dashboard, so now its pretty easy to find out everything. And it was true, that it needs a feeding pump, because before there was problems with starting the car. If it started, then it ran just well. After intsalling a Holley performance feeding pump, it starts just nicely and runs like a sportscar

But does anyone know, what to do with the brake fluid level indicator? As my suburban tank does not have such plug, then i just leave it there hanging? Actually I dont like the light in the dashboard, that says, you have too little brake fluid. And as handbrake uses the same light, I just cant disable it.