3FE wiring

[ccasteel]

I'm replacing the cobbled up wiring for my 1978 converted to 3FE. Hopefully when I get all my questions answered, this can be a resource for others tackling this conversion. What I know for now is that the engine harness goes in with no modification. I'm trying to modify my cowl/firewall harness and my ignorance has me scratching my head a bit. I have gotten a bunch of help from the forums and particularly @tornadoalleycruiser.

If the wires went straight from the ecu to a relay or sensor it would be a lot easier. But, there are many wires that run to other connectors and are spliced into, and out of, main runs. My progress has slowed down immensely and the family as starting to ask when it's gonna be done.

 

[ccasteel]

Does anyone recognize the blue and white connectors in the pics. Both set are inside the firewall with one set by the drivers side and one by the passenger? I think they may run to things like power windows and mirrors. Can I remove them and everything related? The firs pic is the one near the driver and the second the passenger. They are the same style connectors on both sides.

 

[ccasteel]

How about this white connector? It is behind the dash and very close to the fuse box.

Also, I don't know if it matters much, but the cowl harness is from a 1989 FJ62.

 

[4Cruisers]

In your second post, the blue and white connectors are for all of the FJ62 wiring to the rear of the front doors:

Left - rear drivers side door power window/door lock, rear hatch power door lock, rear speakers, rear washer/wiper motors, fuel pump/sender, rear door courtesy light switches, tail lights, rear side marker lights, rear cargo area dome light.

Right - rear passenger side door power window/door lock, rear heater, parking brake indicator, A/T oil temperature, neutral indicator light, seat belt warning light, etc.

 

[lelandEOD]

A lot of the large gauge and predominantly blue wires are for the power door circuits and can all be deleted.

The way I approached the wiring project was to:

Completely unwrap the FJ62 harness.

Select and remove any unnecessary connections and wiring (power windows, cabin
lighting, A/C, seatbelt control, transmission, etc) -basically everything except those components that drive the ECU and send/receive signals between the ECU and engine.

Use the FSM wiring diagrams and start selecting, tracing, and deleting any un-needed circuit.

Lay the FJ40 harness next to the FJ62 harness. This is useful as it gives you an idea where the new 3FE leads need to terminate or be routed to as the 40-harness obviously fits well under the existing dash and around the fenders.

Working circuit by circuit, trace each wire and terminate it to its appropriate point.

For me, the most difficult task was splitting the switched ignition power into two circuits using an added relay. This kept too many amps from being forced through the wimpy FJ40 ignition switch. There are some really good tech articles and how-to's out there that helped me immensely.

Tips:
At some point, I opted to graft the existing FJ40 fuse panel leads to the FJ62 ATC box (see my 3FE/resto-mod thread) and it turned out very well.

I'd recommend investing in a Brother LabelMaker though; scratches on painter's tape gets old quick.

Another good tip is to buy yourself a roll of those velcro cable ties for AV equipment. I use them to hold the harness together temporarily (to keep it organized) but easy to come apart to add/change stuff.

Keep at it. It'll get easier.

 

[pappy]

Go here: http://bushrat.hdcruisers.org/3FEconversion.pdf

Page 8 list the connectors and wires on the cowl harness you need to keep. The rest are scrap.

 

[ccasteel]

@4Cruisers thanks for the detail for each of those connectors. Otherwise I might have missed the fuel pump wires which I obviously need to keep.

@lelandEOD I'm working with 2 different versions of the FSM schematics. Each is very similar, but with different details emphasized. I was trying to follow your approach, but I got confused with all the splices. I'll take another whack with a fresh mind and eyes.

@pappy That is a great link. On my wiring schematics I circled everything I thought was referenced in the bushrat document. The only thing that would have been more helpful would be if there were pictures of all the connectors.

Thanks a bunch guys. Slow and steady will win this race eventually. I've got the slow down pat, now I need to work on the steady.