Builds The Truck of Theseus

[gnob]

CANBUS is actually pretty cool on the engine/sensor side. I think auto manufacturers got carried away with how it’s integrated into every part of modern cars but on the engine side I should be able to pull super detailed realtime engine health numbers.

The big problem is outside of some basic commands that get pushed to the OBD port it’s all proprietary and specific to each manufacturer so it needs to be reverse engineered before I can do anything useful with it…

when your seat can disable the entire vehicle, all that garbage should be tossed.
and while agree about "real time" data, it's pretty rare that typical scan tool data isn't sufficient.

proprietary anything on vehicles should be outlawed.
vehicle tech is like level 100, while consumers are stuck at 10. so much unnecessary trash in newer vehicles.

 

[littlevulture]

Yeah I'm with you 100% on the horrible implementation of the tech in cars, unfortunately OEMs are only required to convert very basic CANBUS data to the OBD protocol for the scan tool so in general I'm finding anything else requires proprietary software. I went though this whole deal when the DPF started acting back before the car was totaled, turned out theres a huge difference between a generic DPF code from the scan tool and the actual internal CANBUS messages that exactly pinpoint the fault...I had to borrow special software from someone to get that far and it was infuriating. I think CANBUS became mandatory around 2011 which means that most of those cars also came from the factory with a screen, when they made CANBUS mandatory they also should have mandated that all that data could be displayed on the screen for maintenance purposes...no more proprietary software. Newer cars are apparently even worse with network and module level encryption keeping basically anyone but the OEM from maintaining certain parts...I absolutely hate everything about it.

Regarding real time data, the CANBUS message frequency is considerably higher than what comes out of OBD port for scan tools which means you can use it for digital gauges that don't jump and stutter when the value changes quickly. I'd eventually like to make a nice digital panel that displays the critical stuff and changes color when I'm approaching a limit, sort of like an annunciator panel in an airplane. I've got a massive excel file that has thousands of leaked VW CANBUS messages which I'm going to need to reverse engineer if I want a good digital dash. The ECM is will be ingesting raw sensor data for managing the engine and outputs all that data on the CANBUS lines whether I want it or not so I'd like to make use of it to keep tabs on the engine.

 

[littlevulture]

Harness is cut away from the OEM fuse panel, I think I know which fuses all the wires go to. There’s only one relay on this panel but there’s two more I’ll need to integrate from the body side of the harness that trigger the primary and auxiliary electric fuel pumps…this harness is a mess.

 

[jgranthevagrant]

A braver man than I. I'm mostly a 1 circuit at a time type.

 

[littlevulture]

A braver man than I. I'm mostly a 1 circuit at a time type.

Unfortunately the way everything was loomed together this was the only practical way I could think of to get everything detangled so I could clean the goop off the wires and get the necessary stuff sorted from the unnecessary...1 wire at a time definitely sounds like the safer option though.

 

[littlevulture]

My goal is to have everything eventually integrated into one fuse box in the engine bay but thinking through my current wiring mess I might get a cheap fuse/relay box like this to get the engine online independently first. I think in the long run it'll save me lots of time and maybe a bit of money too, never done wiring so this seems like an easy way to break a big task down into something more manageable.

Something like this

 

[aztoyman]

Those relay/fuse panels are perfect for this stuff. I don't know what the quality of the relays are. Hopefully they are a "standard" pattern and an easy swap to a Bosch or other quality relay. Or maybe the relays are decent?? I've had a couple China relays that came with some cheap off road lights that have been holding up.

 

[littlevulture]

I think I’ve finally got a grasp on this harness. Still have some studying to do with the wiring diagrams to sort out the fuse/relay situation since the OEM setup had multiple busses embedded in the fuse box. It seems like most of the harness is necessary, first picture is stuff I think I need and the second is stuff I can remove. I count 9 fuses and 1 relay required from the original harness. The ECM provided the trigger for the primary and auxiliary electric fuel pump relays in the body harness, I think I’ll combine those to 1 relay triggered by the ignition in the “ON” position to help with bleeding the fuel system after filter changes and maintenance so that’ll bring the relay count up to 2…these common rail diesels have a lot going on to make them run.

 

[aztoyman]

The days of swapping in a Flathead Ford or Small Block Chevy are LONG gone. Seems like you're "In the zone" to get your harness figured out. I'm still following along.

 

[littlevulture]

The days of swapping in a Flathead Ford or Small Block Chevy are LONG gone. Seems like you're "In the zone" to get your harness figured out. I'm still following along.

Yeah I'd have to agree...back when I was in the market for one of these trucks I saw a 1985 swapped with a Mercedes OM617. Not that any swap is simple but it looked way simpler than this.

---

The ECM uses two different sub-harnesses, a 60 pin that is all on the engine and a 94 pin that wrapped around the engine bay and integrated with the body harness. Not every pin in each connector is used but there are still lots of wires. This is all on the 94 pin connector, the 60 pin is mostly preconfigured, not much to do with it yet. This breakdown is ONLY from the 94 pin connector and doesn't include all the flying leads I have on the other end of the harness for various connectors/power/ground. Termination naming came from the OEM wiring diagrams I downloaded for my specific donor VIN from VW erWin and converted into my own more readable wiring matrix. Despite using my VIN to get the diagrams I have found 2 mis-colored wires so far. I'm mostly taking the time to write this out in case someone else attempting this swap discovers my thread and wants to compare ideas.

NOTE: I haven't talked specifics with a tuner yet but here's my pre-analysis on what to keep from the 94 pin.

Main power and ground for the ECM to use/distribute (I'm guessing right now but these are much larger wires than the rest)
Pin 1 - Ground
Pin 2 - Ground
Pin 3 - Engine Fuse 13
Pin 4 - Ground
Pin 5 - Engine Fuse 13
Pin 6 - Engine Fuse 13

Mandatory Sensors
Pin 8 - Accelerator Position 2
Pin 13 - Accelerator Position 2
Pin 15 - Accelerator Position 1
Pin 16 - Coolant Temp
Pin 17 - Charge Air Temp
Pin 18 - Mass Airflow
Pin 23 - Mass Airflow
Pin 30 - Air Intake Temp
Pin 39 - Mass Airflow
Pin 53 - Accelerator Position 1
Pin 54 - Accelerator Position 2
Pin 55 - Heated O2 (pre-cat, assuming closed loop fuel maps)
Pin 56 - Heated O2 (pre-cat, assuming closed loop fuel maps)
Pin 66 - Air Intake Temp
Pin 73 - Heated O2 (pre-cat, assuming closed loop fuel maps)
Pin 74 - Accelerator Position 1
Pin 77 - Heated O2 (pre-cat, assuming closed loop fuel maps)
Pin 78 - Heated O2 (pre-cat, assuming closed loop fuel maps)
Pin 83 - Charge Air Pressure
Pin 89 - Ground (for various sensors)
Pin 90 - Fan (I'm assuming this is the trigger wire)

Engine Health
Pin 9 - EGT Probe 1 (pre-cat)
Pin 67 - CANBUS Low
Pin 68 - CANBUS High

Other Stuff
Pin 20 - Automatic Glow Time Control Module (discrete glowplug controller and relay)
Pin 21 - Brake Pedal Switch (might be useful for cruise control later)
Pin 33 - ABS Module (might be useful for cruise control later)
Pin 46 - Fuel Pump Relay (likely moving this to be triggered by the key in "ON" instead of by the ECM)
Pin 61 - Automatic Glow Time Control Module (discrete glowplug controller and relay)
Pin 63 - Clutch Position (might be useful for cruise control later)
Pin 65 - Generator (generator=alternator)
Pin 69 - Terminal 30 Power Supply Relay (still need to figure out exactly what this relay powers)
Pin 92 - Terminal 30 Power Supply Relay (still need to figure out exactly what this relay powers)
Pin 93 - Positive Crankcase Ventilation Heating Element (apparently the PCV can freeze in the winter without this)

 

[littlevulture]

I wanted to have the wiring prototype done by Thursday but we had some severe weather that knocked a bunch of trees down (101mph recorded at the airport) and killed my power for 36 hours so I’m just now getting started on it. Changed the plan a bit, I’ve got two cheap blue sea style boxes, one is hot battery and one is triggered by a ECM via a relay. This “should” mimic the VW setup. Also got an inline MAXI type fuse holder for the 50A glowplug fuse…it’s in the right side of the picture by a normal inline holder. It’s comically large in person.

 

[littlevulture]

One day and about 75’ of the cheapest split loom I could find I’ve turned a spaghetti mess of wires into more of an octopus. I still have to sort out power for a couple sensors, fuel pumps, and connections to a battery but the wiring prototype is probably 80% complete…assuming I’ve got the wires sorted right.

I’ve always disliked working with corrugated split loom but I resent it now…

 

[aztoyman]

You're getting there. Wiring like this kinda sucks but you know ya gotta do it. And you'll be happy you did when it's over.

 

[Lucille]

Nice work on the wiring. I wouldnt have wrapped it until you tested it out first. Just in case you needed to move stuff around or add a wire to a leg.

 

[littlevulture]

You're getting there. Wiring like this kinda sucks but you know ya gotta do it. And you'll be happy you did when it's over.

Definitely not fun, although I imagine it’ll be very satisfying when it’s all done EXACTLY how it needs to be for my particular application.

Nice work on the wiring. I wouldnt have wrapped it until you tested it out first. Just in case you needed to move stuff around or add a wire to a leg.

This is all temporary, even after I sorted it was still a tangled and sticky mess from whatever adhesive they used in the loom. It should be pretty easy to deloom a section to modify it if I need to while I work on getting it running. Once it’s running and in the truck my plan is to spend some time deciding on optimal routing, then I’ll redo it all shortening/extending wires as needed and consolidating each branch of wires where it makes sense. For now though I think having each circuit isolated like this will simplify testing and its definitely helping me understand the wiring process…this is my first attempt doing any major electrical work so hopefully that time investment to understand stuff is time well spent long term.

 

[littlevulture]

Test stand is mostly setup, sheathing each individual circuit definitely made this much easier. Still need to dig through the wiring diagram and sort out those last few sensor power leads that went to the fuse panel inside the car and also setup some sort of temporary fuel tank.

Also revived an old laptop with a fresh windows install and ordered Ross-Tech VCDS which is the most common software to interface with these engines. Most of the sensors won’t be providing accurate data to the ECM since I don’t have any of the intake/exhaust mocked up but for a quick test run to test the harness it should be ok? I’ve only used VCDS a couple times but I’m pretty sure I can individually check each sensor as long as they have power and make sure everything is within spec before I try starting it.

I’ll also probably put some outriggers on my dolly contraption so it doesn’t tip over when I try to start it.

Rear passenger view, I’ve got the ECM clamped onto that upright at the rear.

Driver side view, still need to reconnect the fuses.

Really old windows install (2015) to run VCDS. It runs on modern windows too but this is what I’ve got and I don’t feel like going through the whole upgrade process for a offline shop tool.

 

[littlevulture]

Probably 90% of the way to a test run. Wires are all terminated, just need to get a battery charged and hook it up. I don’t have a fuel pump handy to act as a lift pump so I made a little adapter for a small “diesel” can…I think gravity should be a decent lift pump for a test.

Adapter, flywheel, and starter are mounted and torqued enough to test with. My adapter kit is made by TD Conversions, it seems pretty high quality except all the adapter specific hardware is all standard which really annoys me. However, it uses a 2UZ starter so that’s nice. Also got my turbo feed/drain lines sorted out. I’m sure there’s a couple things I’m still missing but I’ll go through it all a couple more times while I wait on my software to show up.

 

[littlevulture]

My friend who’s a wiring enthusiast came over today and we knocked out the rest of the prototype harness. Didn’t get around to attempting a start but from the little I know about using VCDS everything seems to be powering on properly. Hopefully I’ll get around to starting it in the next few days.

Also installed a modification to the CP4 fuel pump. The original design uses diesel to lubricate the pump and it will fail almost immediately if fuel flow is lost which sends shrapnel through the whole fuel system resulting in the entire thing needing replacement. This little aluminum part from Whitbread Performance isolates the lubrication feed from the fuel rail feed so if it fails the expensive stuff is all safe. It shouldn’t ever be an issue as long as the fuel system is primed before starting but it’s cheap and easy insurance. Kinda hard to see but it’s the shiny new aluminum block in this picture.

 

[aztoyman]

Is it important to use an additive with the CP4 pumps or is it a non issue as long as you have the part you installed?

 

[littlevulture]

Additives shouldn’t be necessary, this engine has 112k on it without any additives and it was healthy when I took it out. Most of the problems seem to have been shortly after they started using the CP4 since this system doesn’t prime with the ignition “on” like older vehicles did…you need software (VCDS) to trigger priming cycles in the pumps. After a fuel filter service people would start the car and destroy the pump since the lines weren’t bled. Once people figured that out the failure rate seems to have gone down significantly. Hopefully I never frag a pump but this’ll protect the very expensive high pressure fuel system parts if I do. I’ll also probably put a small inline filter on the return line to catch any debris before it reaches the tank just in case I destroy a pump so I won’t have to drain and clean the tank too.