Is my 33 missing an extra connector and relay near the ECU location?

[Neostead2000]

Believe me for the past 3 weeks I've been doing nothing but wiring and I've extensively looked through the colored wiring diagram however something still doesn't add up. These two connectors are the only connectors hanging around the ECU location, and there is no relay(s)  attached there either. There is one big latch-type female connector and a smaller 18 pin female plug next to it. The ECU connector itself is not in the picture because I have the engine harness off and still working on it. It itself has two male connectors, one which mates up to the bigger one in the picture with the latch, and another shorter one with 30 pins (some missing). That one does not have a female receptacle at the ECU area so I'm unsure if that's related to A/T, ABS, Attessa or whatever other system.

Car is an 06.1996 R33 GTS-T 25DET Manual non-abs spec 2. It came with no gearbox or engine and no loom so I am starting to think the PO may have pulled other parts of the loom as well? Everything else seems to be there. There are a few relays in the boot, one next to the rear fuse box, one near the boot latch, another (brown) one beneath the cabin fuse box (near driver's feet). Starting to think there is a difference in connector and relay layout between spec 1 and 2?

 

[Duncan]

Firstly, you have a pretty rare spec there for a non-ABS s2, I'm only aware of one other in Aus.

I am99% sure that the ignition and ECU relay are in the engine loom near the ECU connector, so that's why you are not finding them. Their connection to the body loom is pretty straightforward with a battery power feed via the engine bay loom and a start signal via one of those connectors you are holding from the dash loom.

[admS15]

On 13/12/2022 at 11:05 AM, Duncan said:

Firstly, you have a pretty rare spec there for a non-ABS s2, I'm only aware of one other in Aus.

 

Make that 2 others, mine is also a non ABS s2 12/96 build. 

 

For sale, 1 of only 3 known to exist (very rare) 69k firm. I know what I've got. 

[GTSBoy]

OP's car is in Bulgaria, so you can remove his from your Oz count.

[Neostead2000]

9 hours ago, Duncan said:

Firstly, you have a pretty rare spec there for a non-ABS s2, I'm only aware of one other in Aus.

I am99% sure that the ignition and ECU relay are in the engine loom near the ECU connector, so that's why you are not finding them. Their connection to the body loom is pretty straightforward with a battery power feed via the engine bay loom and a start signal via one of those connectors you are holding from the dash loom.

Yeah it's a bit weird seeing a '96 car optioned without ABS. I confirmed this by no module, no  extra brake pipes, no fuses for it and the steering knuckles have not been drilled for the sensors. Cleaner engine bay I guess?

I am still a bit confused about the relay situation, though. From what I understand, the relay that is meant to sit there by the ECU is called an "EGI" relay diagram number 25224C which supplies power to the ECU and keeps the pump primed with key ON. I have seen pictures of looms online, they do in fact have a single relay+connector sticking out of the loom wires just before the ECU plug however on the loom I bought it's not there, there were about 4 wires cut short so I am 99% certain it may have been that relay? If so, could I get a standard 30amp relay from the store or find an OEM one from another Nissan and wire that in?

Also there seems to be 2 fuel pump relays at least based on FAST diagrams. One sits next to the brown defogger(rear) relay behind the driver side kick panel and another sitting next to the rear fuse box. I seem to be missing the front one also. I am just unclear whether somebody pulled those two relays when they took out the main engine loom or if the car never came with those? It also seems to have a TOAD security system installed which I want to remove. It seems to have a plethora of wiring going around that area,  could they have removed those relays because of the system itself? Maybe it doesn't need those so they just deleted them?

In any case I will be doing a fuel pump rewire which includes a separate 30 amp relay so I guess the other relays wont matter.

What I need to finish is to re-pin and reorganize that medium sized white latch connector so the loom inputs I have match the car-side female plug pins. And I just did some more digging and I think I have a better idea now. There are meant to be three connections at that area next to the ECU. I found a picture of somebody's S1.5 car and it shows nests for the small, medium and big connector. I have the big one both sides, and I only have the female small side. It appears the small and medium connectors are related to the ABS system entirely. This is super weird because my car allegedly is non-abs??? Could someone have taken out the entire system AND also swapped to non-abs knuckles? Seems too much work. Here is a picture I found and labeled over.

[Duncan]

Well, if @Neil sees this thread he might be able to take some pics from his car in this area.  I can't remember how much factory wiring we removed from the race car but not much from memory. Or admS15 might be able to get at that space to confirm too, depending how much interior that car has in.

It is possible/likely that the ABS plug is in an non-ABS car. Somewhere between 0-99% of the ABS wiring will be in a non-ABS car because otherwise Nissan has to have multiple different looms depending on the spec of the car.

As for the cut wires and missing relay, you need to start with the ECU pinout and check which wires they are, either with a multimeter or tracing it by hand. The standard ECU can run without that relay (if you rewire it to IGN power) but it will stop aftermarket ECUs like PowerFC working correctly as they use that relay to save data before turning themselves off when the key is moved back from IGN to ACC.  We never got to the bottom of why, but there are some minor differences between S1 and S2 GTSt wiring.

For the fuel pump, there is an ECU pin (18 I think) that earths when the pump should run (ie couple of seconds to prime when the key is turned to IGN, and any time the engine is running). Ignore all the other factory wiring and connect that pin to the earth side of a suitable relay's coil (relay size depending on what pump you are using, or if you have a big setup it might be a solid state relay), then hook the + of the relay coil and one side of the relay switch to a fused wire to the battery. The other side of the relay switch goes to fuel pump +. 30A is heaps for the standard pump or most basic aftermarket pumps

Finally, re the security system, great idea to get rid of it if you don't have confidence it was wired well as they can become flaky over time. You really need to spend some quality time under the dash if you are, an immobiliser is just a big set of relays that cut key wires like fuel pump or IGN. Generally you can find which wires have been re-routed into the alarm, and reconnect them in the factory loom by matching colours where they were originally cut. Keep in mind the car is easily stolen without an immobiliser though.

[Neostead2000]

Thanks a lot Mr Duncan, those are some great pointers. That also makes sense about the pre-existing ABS provisions even if no module is fitted.

Actually today I made quite a lot of progress and things are way clearer now. I have made a full pinout of the medium sized connector on my car side and I'm halfway done with repositioning the pins on that, as well as taking out the ones not used that feed ABS/AC/ETACS stuff, which are all absent on the car.

My biggest problem seems to stem from the fact that I bought the wrong engine loom altogether. What I thought was a bargain deal at the time ended up causing me way more headaches. I bought an allegedly Neo RB25DET loom from a Y33 or Y34 Gloria but when it arrived I noticed it had lots of bits cut and missing and during the past weeks I've been slowly rebuilding it from scratch. Some of the plugs match but ALL the wires are completely wrong colors so like you suggested, I had to trace literally all the wires.

What I am doing now is looking at the R33 wiring diagrams and using the schematics to make up my own ECCS relay and connections to it, so hopefully that will work. The IGN relay is not needed since I have the igniter built into each coil.

As for the security system (TOAD), it looks to have been installed professionally by a company in the UK way back but as I will be using a standalone AEM ECU, I don't want anything interfering with it. I have already spent some time under the dash looking at stuff but I cannot really determine if anything has been cut up or spliced. The module looks to have its own fat loom installed.

As for the fuel pump, I'm going to be installing a single Walbro GSS342 255LPH unit which should be plenty but I may still run fatter wires to it just for good measure.

 

[GTSBoy]

1 hour ago, Neostead2000 said:

As for the security system (TOAD), it looks to have been installed professionally by a company in the UK way back but as I will be using a standalone AEM ECU, I don't want anything interfering with it. I have already spent some time under the dash looking at stuff but I cannot really determine if anything has been cut up or spliced. The module looks to have its own fat loom installed.

If nothing has been cut, then it is essentially just an alarm, not an immobiliser, and therefore should be less likely to f**k you around. Of course, it's less useful too, but that's the tradeoff with these things.

[Neostead2000]

Just updating some threads I started (because f**k when people never come back to say what happened!!).

After making my own engine loom with the single ECCS relay next to the ECU connector, the car fires up and runs fine with no lights on the dash (aside from the HICAS which I have yet to troubleshoot). The extra connector does in fact appear to be for the ABS module which never came on my car, so it must have been put there from the factory as a default option.

Also the TOAD alarm was easy to remove. I pulled out the cabling from the engine bay (for the extra horn and hood switch), then the signal wire from the trunk latch, and then tidied up the ignition barrel wires from which they got the power from.