R32 GTR wont start, no dash lights, no power to fuel pump

[MrStabby]

After being stopped for 5 mins, tried to restart but not a cough. Turns over quickly, but there's no dash lights and no power to the fuel pump relay (FPCM has been deleted ages ago). Clock and stereo has power (on IGN). Couldnt find any dead fuses.

My first guess is that its ECU related (does that match the symptoms?) its a stock ECU fitted with Nistune. Checked the internal LED but it does not light - is that LED only for diagnostic codes or should i expect it to light on IGN on?

What should i check next?

[r32-25t]

check if there is power to the ecu,

if yes then it’s probably the ecu

if no then look at fuses and ignition switch 

[MrStabby]

Appears to be power to ECU.

Also, if the clock and stereo come on, doesnt that rule out ignition switch?

Another symptom is cant make a CONSULT connection in Nistune (albeit using untested setup)

[r32-25t]

There’s multiple stages of the ignition switch, the clock and radio and etc are on the acc position and the ecu and windows are on the on position 

Make sure there is switched power at the ecu (grab a pin out to confirm which wire it is) and turn the ignition on and off to make sure it’s working 

[Duncan]

You need to check the ECCS relay near the ECU is turning on when ignition does.

Pin 58 should always have battery voltage, but pins 49,59,109 are controlled by the ECCS relay which is what needs to be powered to turn the ECU on fully.

Pin 18 (fuel pump relay signal) should earth for about 3 seconds when you turn the key to ignition to prime the fuel pump, and should always be earthed when the engine is running.

[GTSBoy]

This ^. ECCS relay is suspect #1.

[MrStabby]

I've taken the two green relays behind the ECU out, applied 12V across the signal side and the output switch closed, so they're ok. I assume one is ECCS and the other is IGN Coil from the wiring diagram.

Tested the windows in IGN/ON and they dont work, so i guess that means its likely the ignition switch, right?

[GTSBoy]

Could be. You're going to need and want to break out the wiring diagram so you can start probing around with the multimeter to find where the angry pixies are being blocked.

[Duncan]

Ignition switch is pretty easy to test too. unplug it and identify battery 12v terminal. Then test continuity to other pins when switch is OFF (none), ACC (ACC continuity), IGN (IGN and ACC), Start (IGN and Start).

There are also a series of fuses and relays at driver's knee in that fuse box, since windows are not working that's where I'd try after checking the switch. I haven't often heard of the key switch failing

[MrStabby]

Ok, the switch connectivity matches your information. Re-checked the fuses and all good.

Perhaps the immobilizer has died? The alarm beeps on and off and opens/closes the door locks, so its working to that extent. Will checking the immobilizer involve finding where its wired into the IGN circuit (assuming that's the case) and verifying it closes the circuit when its disabled or is there more to it than that?

[admS15]

What brand is the alarm? I had a similar issue in an m35 a few years back, no dash lights, no crank but alarm would beep/unlock. It turns out one of the relays on the alarm unit for the immobilizer was sticky and wouldn't activate. Found the unit and tapped the relay with a screw driver a few times and it started to function again. Im pretty sure it was a mongoose alarm system and said relays where built in to the unit.

[MrStabby]

Cant remember the brand (could be mongoose) but it was installed in 2008.

Where was the unit? Was it a removable relay?

 

[Duncan]

Well the immobiliser box is basically just a receiver for the key fob and a set of relays to immobilise circuits like ECU power, fuel pump, ignition (whatever the installer chooses really). generally the wires in and out are all coloured black to make it hard to bypass (but also hard to troubleshoot). you might be able to trace the wires to where the original wires were cut and redirected via the unit to temporarily bypass it. I'd be looking for the IGN signal to ECU as it seems the ECU is not turning on (pin 45).

[admS15]

On 07/01/2023 at 12:46 PM, MrStabby said:

Cant remember the brand (could be mongoose) but it was installed in 2008.

Where was the unit? Was it a removable relay?

 

Unit was buried in below the dash but I was able to locate it with a torch. The relay was built in/soldered on to the main board. I simply reached up with a long screwdriver and tapped it a few times and it unstuck.