Swap wiring

[JD1964]

Donor vehicle is a 1994 Z28 LT1. Recieving vehicle is a 79 Malibu Wagon. The wagon will get the LT1 engine and its 4L60E transmission. I have the entire donor car. I know I need the engine harness, ECU, all fuel and ignition sensors required for management. No problem because the donor car was 100% complete. I know I'll need to clear hurdles in mechanical connections, cooling system hoses and such. No problem there, yet anyway.

I need help with simplifying the electrical requirements. From the 94 donor I want to obviously use the engine management things for fuel and ignition. I also want to utilize the diagnostic port, the cooling system fans and relays to be controlled by the ECU as they would be from the factory, and use the ECU to control the transmission as it would do normally.

I thought I would tear into the chassis harness and try and trace everything and remove all the portions I would need. However, I've found out the harness to be quite complex in all its intertwining madness and whatnot. So, I'm here for help.

What is the more simple way to get this done? I know the ECU is the center of it all and I suppose if I learn it's inputs and outputs I can lay things out from there. I dont expect a simple answer to all this but if anyone can point me to a tutorial or give me pointers about the 94 system and how to get it all setup in the Malibu, that would be awesome!

I understand the engine harness and all its sensors so putting that in and connecting the main harness to the ECU is no problem. What I need help with is simplifying the battery power and ignition power sources to the ECU and the connection of fuel pump relay and wiring, fan control relays and wiring and the diagnostic port so I can use it to tune and troubleshoot. I can use the fuse block and relay block from the donor if that helps but I'm also open to alternative ideas there.

Feel free to chuckle at my meager attempt to sort out the chassis harness.

I'm nowhere near frustrated but I realize its time to ask for help.  Thanks in advance for any and all input.

FD857097-9667-40C6-8DD4-6A78F7F22118.jpg7A10C219-C5F8-4F9B-8031-1D1E2C82D069.jpg

[B52Bombardier1]

At least for a later LS engine harness, I looked to simplify things first by removing the circuits I knew I would not need in my 70 El Camino. I knew there would be no rear catalytic converter wiring - it went by by. Same for Evaporative Emissions and Exhaust Gas Recirculation - all gone.

Figure out the relays required for the fuel pump and its wiring. Ditto for fans if they are electric.

Then figure out where your PCM will get mounted which will dictate wire lengths.

Then worry about power. Some things need 12 volts all the time and some need it only with the ignition on.

Basically, divide and conquer. Solve one circuit at a time and you will figure it out.

Rick

[dave w]

http://www.lt1swap.com/1994_f_body_w...ss_schemat.htm

https://www.facebook.com/media/set/?...5211824&type=3

dave w

[JD1964]

I will study the schematic. I’ll compare it to the harness and try to eliminate what I don’t need and keep the rest.

I notice there are 3 fan relays in the large under hood block that I need to keep. Interestingly, the fuel pump relay for the Camaro harness was located under the dash by the factory. I’m thinking I’ll omit ABS relay in the large under hood relay block and locate the fuel pump relay there. I also noticed in the Camaro dash fuse block there are fuses for ECU BAT and ECU IGN. I’m thinking I’ll also locate those fuses in the large under hood block and mount it near the ECU I’m the Malibu engine bay.

Do you think this idea presents any potential concerns?

[steveo]

nope that'll all be fine

i thought the '94 only had two fan relays, but if you have three, then it's a high/low setup, it runs them in series for low, and parallel for high

are you going to run a dual fan setup? if you're running a single fan you can just run one fan relay and disable the second fan entirely. you don't need to use the factory fan relay configuration.

[dave w]

There is the option to use an aftermarket weatherproof fuse / relay box: https://www.waytekwire.com/item/4598...it-Mini-Power/

One box has enough room for 3 fan relays, 1 fuel pump relay, Injector Fuses, PCM Fuses, and Sensor Fuses. The second box is optional for a Starter Relay, Reverse Lights Relay, Ignition Relay and related fuses.

dave w

[In-Tech]

Hi Dave,
Do you like those better than the bussman's?

[JD1964]

nope that'll all be fine

i thought the '94 only had two fan relays, but if you have three, then it's a high/low setup, it runs them in series for low, and parallel for high

are you going to run a dual fan setup? if you're running a single fan you can just run one fan relay and disable the second fan entirely. you don't need to use the factory fan relay configuration.

It has three relays and yes, I plan on running the radiator and dual fan setup from the 94 Z28. It is a multi speed setup for sure. Both fans come on together at various speeds depending on cooling demand. I verified this when I had the engine running in the Z before I pulled it. It fooled me at first as I thought they were not running at all. The are pretty slow and quiet when on the lowest speed. And sitting there idling in my garage, low speed kept the engine cool so I initially though the fans were not working because I could not hear them over the sound if an idling engine.

I think I had read that 94 was kind of an oddball year. The earlier 94's had two fan relays and the latter had three.

We wont be running AC. Is it possible that one of the three fan relays is only needed for the AC function?

Thanks everyone for helping us out on this. All ideas are considered but we primarily want to use as much as the factory stuff from that Camaro as possible.

[JD1964]

I just started studying the schematics Dave posted. Sure enough one of those pages has the comparison between early and late 94 fan wiring.

fan-config.jpg

[dave w]

Hi Dave,
Do you like those better than the bussman's?

I like the Bussman's (mostly for under-the-dash but Bussman's are under-hood also): https://www.waytekwire.com/item/4634...TMR-Mini-Fuse/

Mini-Fuse-RTMR-Micro-Relay_46345_f.jpg

dave w

[JD1964]

Ok, learning as I go.

Coming off the data link connector, wires branch off to SIR, EBTCM and keyless entry. Since I'm not using those systems in this project, I just snip those wires out? Anything further needed there?

[JD1964]

Also, here's an idea. I take the VATS ignition lock cylinder from the Camaro and keep it attached to the VATS wire going to the ECU. I can bundle it up hidden under the dash and keep the VATS resistor key in it. Then use the standard Malibu lock cylinder in the column as normal for starting the car. In the event I want to have some anti theft security, I reach up under the dash and take the VATS key out.

Would this be a viable idea and would I also need to retain the anti theft module and lace its circuitry into the Malibu wiring?

Sketchy, or what?

[steveo]

ditch vats completely and tune it out. its nothing but trouble

[JD1964]

On the other hand, I may want to eventually write VATS out entirely.

Either way, unless I have VATS written out of the ECU, I'm going to need a resistor signal to the ECU right? So meanwhile, what components or modules do I need to retain until sending ECU for flash? Whats the minimum I need to do to bypass for the time being? I see how easy its done on cars originally equipped with VATS, but the end result of this project is obviously not an original configuration so I'm not sure if I need to retain the anti theft module and circuits or not.

[JD1964]

ditch vats completely and tune it out. its nothing but trouble

Thats all I needed to hear, thanks. Consider it done.