GUIDE: Repairing the wiring loom under your radiator

[JSeaman]

It seems there are a number of bizarre electrical faults that can be attributed to the loom underneath the radiator failing, a lot of headlight issues are referenced on the forum and other bizarre oddities. If you find yourself in need of a repair this will hopefully help you do it

Step 1 - Jack the car up nice and high so you have plenty of room to work, ideally get it on hydraulic lifts or over a pit



Step 2 - As you will be spending a lot of time under the car please make doubly sure it is safe, use axle stands and maybe even a second jack just in case, a car only falls on your head once



Step 3 - Look under the front of the car and you will see a plastic undertray (picture 1), there are a number of plastic circles which you need to pop out with a flatblade screwdriver (picture 2). Once the centre pin is release you can pull the clip out (or just the pin) to release the plastic (pin shown in picture 3)

[JSeaman]

Step 4 - Work your way around the front of the undertray removing the 10mm bolts and also the 2 on either side as shown in picture 3





Step 5 - Finish by removing the posidrive screw on either side of the undertray then remove it from the car

[JSeaman]

Step 6 - On either side of the radiator there are 2 12mm bolts holding clamps down, remove these then slide the clamps up off the lugs on the rad





Step 7 - You don't need to disconnect any hoses, simply lift the rad up a few inches and there is a handy little shelf you can ledge it on near the bottom so it sits as shown in the picture



Step 8 - Crawl under the car and you will see the loom which is a bunch of ~20 wires wrapped in insulation tape. Inspect this carefully for signs of damage which could range from swelling to bare wires showing.

[JSeaman]

Step 9 - If you find any problem areas, remove the insulation tape as far back as you need to remove the bad wires and simply cut them out. If there are multiple wires I suggest you do them one at a time to save any chance of mistakes!



Step 10 - Splicing in new wires is simply a case of cutting out the bad wire, stripping the ends then apply solder to the exposed bare wire. Then make up a new piece of wire in the same way and solder the tips together. Unfortunately my loom was OK so I didn't get to take pictures of this but it is a simple process

Step 11 - Once you have reworked all the wires re-wrap the loom in insulation tape and I suggest you don't follow the absurd routing against the rad and metal (I'm pointing to this old route in the first picture) but simply run the loom along he underside of the rad as shown in the second picture.

[JSeaman]

Step 12 - Drop the radiator back down into the mounts as shown (from underneath)




Step 13 - Refit the top clamps and you should be good to go. Pop out for a test drive, check all switches work and then, once you're happy, refit the undertray

[madmodder]

is that a mrk 3 supra i can see in pic 7?

[JSeaman]

Now if you want to talk mk3 Supras I have a lot of time :) Yes, it's my sixth one, guides galore on these ...

http://www.mkiiisupra.net/bbs/showthread.php?t=11469

[madmodder]

Now if you want to talk mk3 Supras I have a lot of time :) Yes, it's my sixth one, guides galore on these ...

http://www.mkiiisupra.net/bbs/showthread.php?t=11469

im a jap fan at heart
supra's are nice cars but for me the mrk 4 is to comman for it to be special anymore, its going the same way for my driving beast which is a shame.

[JSeaman]

The Mk4 has a great engine in the 2JZ but it's all been done before. The mk3 is a real GT with astonishing performance for the money - 232bhp/254ftlbs out of the box and so much scope for tweaking.

I've done pretty much all there is to do on them, currently got a T4, external wastegate, screamer pipe, AFPR, blah blah blah. I spent a half hour on the engine yesterday, I'm pulilng it to do the bottom end because the big ends have let go. I even helped right an article in Practical Classics late last year about them, they called me an expert and everything :)

[madmodder]

The Mk4 has a great engine in the 2JZ but it's all been done before. The mk3 is a real GT with astonishing performance for the money - 232bhp/254ftlbs out of the box and so much scope for tweaking.

I've done pretty much all there is to do on them, currently got a T4, external wastegate, screamer pipe, AFPR, blah blah blah. I spent a half hour on the engine yesterday, I'm pulilng it to do the bottom end because the big ends have let go. I even helped right an article in Practical Classics late last year about them, they called me an expert and everything :)

nice, big ends are a ****, specially if it turnd out to the mains, you gonna have the crank balanced and lightened at the same time?

[JSeaman]

The crank's going to be scrap so I've stripped a second bottom end and am using Clevite 0.25 undersize bearings all round, rods, mains and thrust washers. I just need a few hours to pull the engine and figure out what made them let go then I'll throw my 550cc injectors in and go tuning (Innovate wideband and SAFC)

[madmodder]

The crank's going to be scrap so I've stripped a second bottom end and am using Clevite 0.25 undersize bearings all round, rods, mains and thrust washers. I just need a few hours to pull the engine and figure out what made them let go then I'll throw my 550cc injectors in and go tuning (Innovate wideband and SAFC)

should be good for 450bhp mark if not a little more think 550cc injectores are ok till the 500bhp mark. do 1jz's like a fast run in? i would lighten, balance and have the crank polished, would mean a more responive pull off boost, im guessing you have a lightend clutch and flywheel combo?

[JSeaman]

Yeah I'm aiming for anything around 400bhp, more than that gets really difficult to put on the road with rwd and no traction control!

550s can be pushed harder but it's a safe area for them to be in with ~80% duty cycle and the pressure I'm running for fuel.

"1jz's like a fast run in"
Not sure what you mean by that?

The 1J (2.5 twin turbo) is a different animal to the 7M (3.0 single turbo) and give a totally different feel to the car. I've done lightened, balanced and polished cranks but it yields very little noticeable gain.

The latest one is auto but I've got an R154 to strap to it while the engine's out. Again, had an RPS flywheel (one of the finest) and didn't rate it as much of a gain. The Spec Stg 3 clutch however was brilliant!

The problem with these cars is that they accelerate just as much at 140 as they do at 70!

[blairs40]

my god man !!, that underside is rusty as hell , im so glad we dont have winters here where the roads need salt .....that would almost be a wof(mot) fail over here in good ol new zealand ....
yikes .
cheers mate
blair

[madmodder]

Yeah I'm aiming for anything around 400bhp, more than that gets really difficult to put on the road with rwd and no traction control!

550s can be pushed harder but it's a safe area for them to be in with ~80% duty cycle and the pressure I'm running for fuel.

"1jz's like a fast run in"
Not sure what you mean by that?

The 1J (2.5 twin turbo) is a different animal to the 7M (3.0 single turbo) and give a totally different feel to the car. I've done lightened, balanced and polished cranks but it yields very little noticeable gain.

The latest one is auto but I've got an R154 to strap to it while the engine's out. Again, had an RPS flywheel (one of the finest) and didn't rate it as much of a gain. The Spec Stg 3 clutch however was brilliant!

The problem with these cars is that they accelerate just as much at 140 as they do at 70!

oh a i know they do, 450bhp mark is where they start becoming work to drive, well your gonna be breaking in or running in the new shells, if the engine will tolerate it do a fast run in, a normal 500 miles driving then do 500mil with a bit more get up and go or if you worried about the strengh look at doing a steady 1000 miles then look at doing 500 at a bit more spirited level of rpm, what your looking for with a polished, lightened and balanced crank is how long it takes to get to revs or how much freeier it revs, the only down side to lightening the crank and flywheel is that you lose inertia, and you know when you have gone to light as the car will stall when coming to the lights so you would be looking at holding a little more revs at idle or upping the idle control valve and bring the idle up a little.