89-90 240sx with S13 SR20det please come in! need your service!

[240sx-pat]

So long story short I'm trying to get my car up and running but found out my ECU is messed up, that part doesn't bother me I'm still waiting for my new ECU at the moment but before I plug anything I need verification from other sohc chassie owner with s13 SR20det swap to verify something for me. Need someone with running SR

I just need you to safely disconnect your ECU

put your key in an "on" position check the black/white wire on the chassie side , which goes to SR pin 38 and 47 for ECCS power.

I just need to know if you get any readings with your multimeter with the black/white on the chassie side , not SR side

Also need to check either pin 104 or just black/pink wire on the SR harness and see if you get any readings on your multimeter




I can give you 10 dollars for this through paypal.

[saleaf]

I'm not sure if it helps. But i followed this wiring how to for my swap. SOHC to SR20. in my 90. It worked flawlessly. If i was home i would help you out further. But im not. Good luck either way.

SR20DET Swap Engine Harness Wiring Diagram Guide SR SR20

[240sx-pat]

Oh yea, np and thanks believe me I followed that we even used a different harness that work, but I just need to check this one thing to get an understanding of it all . Another person having the same issue and he has the symtom/result as me that's why.

let me edit that***, we used a known working harness , my ECU is a problem that's for sure now but I need the check those 2 things

[kennn]

On the big grey plug by the battery, on the chassis side is a Black/White thick wire. This power is for the ECU. It's controlled by the ECU relay. The ECU activates the ECU relay with pin 4 Red/Black, i.e. the ECU is sef-activating - it turns itself on and off via the ECU relay.

If you turn the key to ON, you may or may not have power on this Black/White wire on the chassis side. It depends if the ECU is triggering the ECU relay or not.

If you turn the key to ON, jumper the Red/Black wire on the chassis side on the small brown plug next to the battery. Connect this wire to ground. If everything is hooked up correctly on the chassis, you should hear the ECCS relay click. Then you will have power on the Black/White wire discussed above.

Hook up your multimeter to check for voltage 20V. Hit the BLack/White wire and ground and you should see ~12 Volts of battery voltage.


On the brown plug by the battery, on the engine side there is a Black/Pink wire. This is ground for the fuel pump relay. The ECU uses this wire to control the fuel pump relay.

Assuming everything is working correctly on your car, set your multimeter to check for continuity. Connect one prong to the Black/Pink wire on the engine side and the other prong to any body ground. You should get nothing, no continuity.

Turn the key to ON. You should now get continuity to ground while th ECU primes the pump.

[kennn]

If you want to check your fuel pump relay wiring, turn the key to ON. Jumper the Black/Pink wire in the brown plug on the body side to any body ground. You should hear the fuel pump relay click and the fuel pump turn on.

[kennn]

You need the ECU plugged in and working correctly to get power and ground on these 2 wires.

If you unplugged the ECU all you will get is open connection because the ECU controls these signals as discussed above.

[240sx-pat]

Damn, you pretty much answered my question this is the kind of information that I was wanting to know, well quick pop quiz ..here's the scenario, assuming ECU is dead/bad

#1 let's say the ECU is dead, and you checked black/white on the chassis side ..what would you get?

#2 If you check black/pink wire on chassis when key is turned "on" ..What would you get?

I just want to see if you come up with the same result that I'm getting now.

last question, is black/red suppose to be a constant power even when key is "off" or is it only constant power when ECU is dead ?

[kennn]

I PMed you back but just real brief

1. nothing
2. 12V(+)

Neither. 12(V+) with key at ON or ST. Controlled by the ignition switch. Has nothing to do with ECU.

[onehundredoctane]

my thing is, if my ecu is toast, what caused it? I don't want to throw another one in there and fry it too. . .

I went thru the ecu connector and I'm not getting 12v on the black and white wire, can't remember what pin that is. . . 38 or 39? But from what you've said above, the black and white needs to be grounded?

[onehundredoctane]

Well, I've found one problem, hope it's the only thing I have thats messed up. Pin 36 on the ecu is labeled ign switch, I'm guessing that gets 12v when the key is in and switched over. The trace on the board for pin 36 is fried on the circuit board. My first instinct is to get some wire and jumper it thus completing the connection but I'm scared that when I hook the ecu back up its just going to smoke that wire. Anyone? Ideas? Trying to stay cost effective here