Wiring- COMPLETE whole vehicle standalone

[hazard]

Hi all
i am rebuilding My 80 from the ground up. Complete refurbishment and modernization down to last bolt and nut. Thread coming soon. Separate engine thread already going.
as I want a standalone system for the engine, and I want to simplify all the other wiring in vehicle using PDM’s instead of outdated fuses and relays, I have some questions for all you wiring gurus. I am very good at wiring and love reworking things to improve routing etc., but there are some things I haven’t delved into yet.
main question is:
if I go full standalone ecu and tcu, can I remove my ecu and tcu as these will be controlled by standalone units?
main thing is: do I need the ecu/tcu for other systems such as abs, air conditioning, and a few of the other “computers/controllers” in the 80?
or do all these computers act as standalone that could just receive power only from a dedicated PDM circuit.
basic circuits that do not require a controller/computer, such as lights, wipers, horn etc., are not an issue, only things with a controller.
comments and thoughts on this please.

 

[bryson]

This is a HUGE can of worms and there is about a zero percent chance it'll be worth the effort. So many things on an 80 are controlled by modules/computers... ABS, lockers, wipers (there is a module for intermittent wipers on your front AND rear wipers...), climate control, gauges, plus dozens more systems - And I really don't think they all work as independent systems. No way you could build something simpler than the existing wiring without using all the factory modules. And, the most important question here is why?

 

[LandLocked93]

Sounds like you need an OBD1 80. lol
Reliability and redundancy. Which are you after?
Just my hot take on what I understand you to be doing...I'd leave all factory devices in place and add the stand alone systems that you want. Thought being that if the stand alone systems fail, you can 'swap harnesses' back to the factory devices and keep rolling.

 

[audi2nr]

you can remove the ecu/tcu and a lot of other wiring and fuses want and run say a haltech nexus ecu and pdm for this. it's going to be lots of work but luckily the 90's electronics were pretty simple, yes lots of things had control modules for thing like a/c, abs but you can keep those intact and the latest standalones are vastly smarter and can supply pretty much any signal those modules might need to operate. but like i said, there will be lots and lots of rewiring. looking forward to seeing your 6r80 progress... i wouldn't mind adding an 80 with a modern transmission to the fleet.. i forgot to include that haltech has flying lead harnesses for the pdm that will simplify some stuff but you will have to run the wire and bundle it and terminate it to whatever components you have.

 

[smritte]

I have been looking into changing most of my relays and fuses for solid state controls. This is where I find road blocks. Finding generic "solid state" controllers is the issue. There's a handful of companies making them but I want to still use my current switch's and not their interfaces. I also don't want Bluetooth. Building my own controllers is a bit more work but will probably be what I do. I'll be following those threads in case you find something I didn't.

 

[PIP]

Yes, You can remove the ECU (only 94 and older have TCU) and nothing will care.

80 series wiring is really good. I've been doing automotive wiring projects for over 2 decades. I think you will have a very difficult time emulating the same quality Toyota put into the original harness.

What is the perceived deficiency with fuses?

I have 8000 sq ft of shop space and a couple million lbs of CNC's wired with fused on 400 amp 600 volt Square D I-line busway. Fuses are awesome. They always open when they are supposed to. They don't open when they're not. Fuses don't care about external interference. They don't care about odd frequencies, voltage fluctuations or temperatures. They only care about current.

Fuses are standard, easy to get anywhere. Always work.

Breakers not so much. They wear out, they lose current capacity over time. They have contacts that oxidize, foul and generate heat.

Breakers are not always better. Especially when they are something trendy that is obsolete in 5 years.

 

[hazard]

I am a perfectionist and this build is my dream. And I love wiring. I realize it will be extremely complicated. That is the part I like.
I don't believe here really aren't that many controllers that require ecu input and most of my stock switches and dash will be replaced by something else.
Keep the comments coming, especially if you have actual experience with the systems.
Primary concern is something like ABS. Lockers dont need computer, and probably not AC.
What other systems might be controlled by ECU? I have the car completely torn down and all the parts pile up. Just going by memory, the only control unit I remember is ABS. Also wondering about intermittent wiper control, but as there are kits to add to older cars it should be easy, high low is easy. Quick look at wiring diagram I see a number but most are relays. except the following: ABS, Diff lock, center diff lock control, cruise control (a big one I need that may be an issue), shift lock ecu ( a safety item i don't really care about ( I grew up driving before all these safety items),.
I think my main concerns are ABS (which I like only for snow driving), and cruise control.

 

[PIP]

You can answer all these questions with the EWD manual.

And that begs the question- When you have rewired everything full custom are you going to make your own 150 page EWD that documented what you did?

 

[hazard]

Yes, You can remove the ECU (only 94 and older have TCU) and nothing will care.

80 series wiring is really good. I've been doing automotive wiring projects for over 2 decades. I think you will have a very difficult time emulating the same quality Toyota put into the original harness.

What is the perceived deficiency with fuses?

I have 8000 sq ft of shop space and a couple million lbs of CNC's wired with fused on 400 amp 600 volt Square D I-line busway. Fuses are awesome. They always open when they are supposed to. They don't open when they're not. Fuses don't care about external interference. They don't care about odd frequencies, voltage fluctuations or temperatures. They only care about current.

Fuses are standard, easy to get anywhere. Always work.

Breakers not so much. They wear out, they lose current capacity over time. They have contacts that oxidize, foul and generate heat.

Breakers are not always better. Especially when they are something trendy that is obsolete in 5 years.

Part is just for fun, part is my experience with boats. I have rewired many boats with a high amount if circuits. I always use a breaker panel rather than fuses. They have been far more reliable in a harsh saltwater environment. I especially like having a dedicated circuit for each and every item as it is so much easier when it comes to diagnostics and repair. Not sure about PDM's but all my experience with solid state items elsewhere has shown then to be very reliable. If I did all circuit breakers it would be more wiring and real estate than a PDM and PDM's offer you diagnostics for current draw etc.

 

[hazard]

you can remove the ecu/tcu and a lot of other wiring and fuses want and run say a haltech nexus ecu and pdm for this. it's going to be lots of work but luckily the 90's electronics were pretty simple, yes lots of things had control modules for thing like a/c, abs but you can keep those intact and the latest standalones are vastly smarter and can supply pretty much any signal those modules might need to operate. but like i said, there will be lots and lots of rewiring. looking forward to seeing your 6r80 progress... i wouldn't mind adding an 80 with a modern transmission to the fleet.. i forgot to include that haltech has flying lead harnesses for the pdm that will simplify some stuff but you will have to run the wire and bundle it and terminate it to whatever components you have.

My engine block is now in the adapter shop getting designed for trans adapters. Going to go forward, no hitches yet.

 

[hazard]

You can answer all these questions with the EWD manual.

And that begs the question- When you have rewired everything full custom are you going to make your own 150 page EWD that documented what you did?

It will actually be a much simpler wiring diagram. One thing I noticed on the 80, and most other vehicles, is there is a huge amount of wiring that is redundant. Wires that are there for different models and options. They are blank or empty. These will all be removed. I will actually keep most of the harnesses, as long as they are in good shape, such as all the wiring to the rear of vehicle for lights etc., just removing the above mentioned not used wires.

 

[PIP]

Part is just for fun, part is my experience with boats. I have rewired many boats with a high amount if circuits. I always use a breaker panel rather than fuses. They have been far more reliable in a harsh saltwater environment. I especially like having a dedicated circuit for each and every item as it is so much easier when it comes to diagnostics and repair. Not sure about PDM's but all my experience with solid state items elsewhere has shown then to be very reliable. If I did all circuit breakers it would be more wiring and real estate than a PDM and PDM's offer you diagnostics for current draw etc.

How have circuit breakers been more reliable than fuses in a salt water environment? Current is current. Corrosion is corrosion. I spent 4 years of my life out in the ocean on a ship with 4 megawatt electrical system. There are considerations for a salt water environment, but it doesn't change any fundamentals.

Look, my point is don't be a sucker for every new gadget. Wiring takes a lot of work and knowledge that isn't apparent at first- Like documenting what you did and proper wrapping and routing. Here's a big one- Where are you getting your wire? Are you buying top shelf electrical supplies? Because all too often folks will buy into some well marketed, overpriced electrical nonsense and then hook it all up with cut rate Chinese wire that falls apart in 5 years.

About 15 years ago I witnessed the consequences of a very large OEM cut wiring costs by switching to a lower cost wire wrapping product. That $5 per truck they saved cost them 50 million in warranty wiring harnesses.

 

[hazard]

How have circuit breakers been more reliable than fuses in a salt water environment? Current is current. Corrosion is corrosion. I spent 4 years of my life out in the ocean on a ship with 4 megawatt electrical system. There are considerations for a salt water environment, but it doesn't change any fundamentals.

Look, my point is don't be a sucker for every new gadget. Wiring takes a lot of work and knowledge that isn't apparent at first- Like documenting what you did and proper wrapping and routing.

I agree with some of your thoughts. mainly that proper wiring, (design, materials and techniques etc) is the most important part. I also agree that current is just current. I won't argue about fuses vs relays as I have my opinion on that, especially if you are remote and can't find the products you need for repair. I have made many fuses with cigarettes' tinfoil to save my bacon. You are obviously highly knowledgeable on wiring, but this is really quite simple, and low current, compared to what you do. Besides, wiring is fun and I just want to do it to see if I can, and I like new tech.

 

[hazard]

Also, I don't mean circuit breakers are more reliable than fuses. However, you need many different fuse on hand, which is not always possible.

 

[bigredmachine]

there are some things that are stand alone like the abs, ac system that wont need ecu input. best bet is going to be get an ewd, read and reread the how to use this manual section then dive in. there is a lot of good general info in the front of the ewd that even if you have experience, and it sounds like you do, its still worth reading.

 

[PIP]

Also, I don't mean circuit breakers are more reliable than fuses. However, you need many different fuse on hand, which is not always possible.

What I am saying is that fuses are superior because circuit breakers wear out and that will ruin your day 10 fold over not having the correct fuse on hand.

Fuses do not have contacts. They have an element that melts. The contacts in breakers foul over time.

Here's a way to think of it- The part that melts in a fuse is the part that opens the circuit. Super KISS. In a breaker, the mechanism that opens the circuit is separate from a heater that makes that mechanism work. A breaker has atleast two separate elements to it. What I see is almost always the breaker failure mode is that the contacts go to sh!t, but the heater part works fine. This leads to the breaker contacts being the choke point in the circuit and the breaker has a meltdown without ever tripping.

Fuses can't do that. Nothing to malfunction. If your fuse pops and you don't have a replacement you can make a fuse. You can't make a circuit breaker.

 

[hazard]

Thanks. I have the EWD and have used extensively.
Cheers

 

[hazard]

What I am saying is that fuses are superior because circuit breakers wear out and that will ruin your day 10 fold over not having the correct fuse on hand.

Fuses do not have contacts. They have an element that melts. The contacts in breakers foul over time.

Here's a way to think of it- The part that melts in a fuse is the part that opens the circuit. Super KISS. In a breaker, the mechanism that opens the circuit is separate from a heater that makes that mechanism work. A breaker has atleast two separate elements to it. What I see is almost always the breaker failure mode is that the contacts go to sh!t, but the heater part works fine. This leads to the breaker contacts being the choke point in the circuit and the breaker has a meltdown without ever tripping.

Fuses can't do that. Nothing to malfunction. If your fuse pops and you don't have a replacement you can make a fuse. You can't make a circuit breaker.

All agreed in principle. I have never had a circuit breaker go bad on any of our companies machinery, we have 70 pieces of heavy equipment. And, in a pinch I can always remove circuit breakers and create a makeshift fuse. But in all honesty, when I do wiring jobs I seldom have problems, mostly its the unit at the end of the circuit that is the problem, I just use the fuses or breakers to tell me there is a problem. With a PDM you can actually log the current draw, historically and real time, to really help with diagnostics. We will see how reliable solid state "circuit breakers" turn out to be. One cool thing is that PDM's can be programed to retry circuit with a settable amount of tries, and a settable amount of tries, before a complete shutdown. This is helpful as sometimes we have an odd spike.
Cheers

 

[Malleus]

As @PIP said, the answer is in the EWD; just start at the ECU and work out from there. I've never thought about replacing the entire harness system, so I never looked at what the ECU is or isn't connected to.

Ignore the haters; I think this is a way more useful effort than building an electric 80.

 

[hazard]

Hi again
after some quick research I now realize this is completely possible. My main concerns of abs and cruise control can easily be dealt with by using available aftermarket stand alone systems ( more cost of course, but this is not meant to be a budget build as you will see when I start my thread). if I can’t make the stock systems work. The abs aftermarket systems are also much more modern with many adjustments available.
so really now the only thing I would be missing is the OBD system. Not really sure I will need, we never used to have, as using standalone ecu allows me to set warnings for virtually any parameter, such as low voltage at an O2 sensor, or a bad air fuel ratio etc., probably even more than a stock OBD system.
now the question is; do I want to do it.
not sure yet. I will definitely improve wiring by getting rid of redundant wiring. Will be using stand alone trans control and PDM’s. Then I will see what stock systems I can make work before I decide.
am also waving pro/cons of drive by wire. Personally hasn’t been something I like in my stock vehicles, but it has a number of positive attributes whe see with an aftermarket ECU.
anyone have any more comments or advice?
cheers