Jump to content
SAU Community

Recommended Posts

Hey guys, first post so make sure if its incorrect, etc. drop a comment down below showing my how to fix in the future.

 

Got a no start on my RB20DET R31.

Information prior to the no start condition:

Car was idling, has been running for weeks fine, recently fixed a leaking o-ring at the fuel rail, and while it was idling after the repair i was attempting to get the cluster temp guage working from an RB30e temp sender to the single spade connector on the factory 20det harness. Accidentaly tapped/bumped the spade (connected to the harness) against the block / thermostat plumbing and the engine just cut out and died instantly. No sputtering, etc. died as if the key had been turned off, very strange and could only imagine its some voltage serge situation.

Information relating to my diagnosis that may or may not be relevant but i thought id include:

- Fuel pump can be heard running on "ignition ON", FPR reads 0kg/cm fuel pressure, but increases to around 1-2 (30-40 or so psi) when the hose is squeezed.

- Secondary ECU has been trialed that is believed to be healthy but haven't tested for myself, only word of mouth.

ECU Pins: 

50/60 - Closed circuit 

10/20 - Closed circuit

107/108/116 - Closed circuit 

26 - Closed circuit 

58/49/59 - 12v + (ONLY WHEN PIN 16 IS MANUALLY GROUNDED)

109 - 12v + 

45 - Believed to be possible open circuit, will be re-checking and updating asap.

Extra notes: 

ENGINE CRANKS FINE.

- Pin 16 has 12v to the ECU harness but does not activate ECCS relay when "ignition ON". BUT when manually grounded to chassis (bypassing ECU) ECCS relay activates and pins 49/59 recieve 12v+ to the ecu harness.

- CAS has ground and 12v+, when spun by hand 1 degree wire cuts 5v respectively (per 1 degree), but the 180 degree seems to be all over the place, more like 20 degrees separation. Also when spun by hand, injectors and coils CAN NOT be heard firing.

- Injector 6 has been tested with a noid light on crank and revealed NO pulsing, entire rail has also been tested out of manifold with no injectors visibly firing on crank.

- Coil 6 has been tested with a plug in the boot, out of the head and no spark was seen.

P.S Ignore the scribbles on the photos, most are there when i've gone on tangents and probably reveal nothing about the problem, just me trying to clear the diagrams in my head, I included them simply for reference in the event they are incorrect / outdated, etc.

Any help is appreciated at this point, it's probably really obvious but i'm driving myself crazy over the past couple weeks with this and as im beginning to take on more work i have less time to goose chase and need to regain a sense of direction for what i should be investigating, thanks!

- Sam

 

COMPLETE HARNESS.jpg

ECU PINOUTS.jpg

Link to comment
https://www.sau.com.au/forums/topic/475284-r31-rb20det-no-start/
Share on other sites

50 minutes ago, GTSBoy said:

Surely it has to be a fuse?

If you could point me to where i would be finding fuses for the ECU, etc. on an RB20 swapped 31 / rb20 loom that would be appreciated, the engine cont. fuse (factory fuse box) under the wheel is good and as far as ive been able to find, the rest related to the ECU would be the fusible links, which i have checked and are all ok 

Nope.  Sorry.  Not my cup of tea.  Just seemed like you had the "Shorted something (your temp gauge wire) out.  That something is not directly connected to the ECU, so probably didn't burn anything in the ECU" type of event that usually then leads to a fuse popping.  Some parts of your system still have power, but others don't.  Sounds like a fuse.

Update to my findings.

Found that the ignition relay (pin 1) had no continuity, so manually grounded it, completed the relay circuit but still did not change the no start condition.

Pins 43/45 Also had low/no voltage, but unsure if that should be the case or not, pointers would be helpful.

 

RB20DET WIRING DIAGRAM.jpg

Edited by colata

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Time to decide what’s more import, your power level or your budget because you’re going to struggle to keep both 
    • Our Southern Highlands Cruise is proudly registered with “R U OK?” Day.  Sometimes the best way to check in on your mates is by getting out for a drive together. Sharing a common passion like cars creates the perfect space to chat, connect, and support each other.  A simple “R U OK?” can make all the difference. Let's enjoy the drive, the company, and look out for one another. PLEASE WEAR YELLOW FOR “R U OK?” DAY Sunday 14th September 2025 9:30AM Meeting Crossroads Homemaker Centre 10:00AM Cruise Departure Via Old Hume Hwy 11:45AM Arrival at Mittagong RSL Club Meet Location: Crossroads Homemaker Centre Final Destination: Mittagong RSL Club *Disclaimer* There will be a lead and follow car so no one should get lost. If you would like to attend or bring others along please put your name down and a +1 as numbers will be needed prior! This is NOT a race and we will all be adhering to all road rules. If this is what you want please come to one of our many track days. This is an official SAU:NSW event and will be run under a CAMS permit. One of the things that really sets our club apart is our commitment to being true enthusiasts. When on normal roads we strive to maintain good relations with the authorities as well as the public in general. When attending one of Skylines Australia NSW events please try to: • Be aware of surrounding environment and act accordingly. • Drive courteously on the state’s roads as a true enthusiast should. • Understand how important it is to maintain the good name of SAU NSW and thus, treat others accordingly. • Any misbehavior will not be tolerated and you will be asked to leave.
    • Yep, its been down for a while, as I understand it it will be back soon.
    • Yeah I also looked at Plazmaman, but, it ended up alot  cheaper getting black ones through EFI when you also added in the delivery cost
    • Nice shot! They look super clean. The roof rack delete on the black one is interesting. Would like to see more pictures from different angles. It's subtle but could make quite a difference to how the car looks in profile.
×
×
  • Create New...