ECU Power?

[black14]

Hi everyone,

Chasing an electrical issue on my 2008 - CHEC on dash, no fuel pump prime, no immobiliser handshake. Everything else appears normal - e.g. clock sweep, dash backlights, headlight, tail light, brake light, neutral light, indicators, horn etc. Engine will crank when starter button pushed.

Bike running normally before switching off to refuel - fault apparent when trying to restart afterwards.

ECU in another bike, fuel pump fires momentarily (but not for the normal 3 second prime), immobiliser handshake occurs (and fails as key/ECU mismatch), but still ends with the same symptoms as above (i.e. CHEC on the dash).

Have eliminated side stand switch and relay, kill switch, clutch switch, fuel pump and relay and bad earths (frame/engine to battery) as causes. All connectors checked and cleaned.

According to the manual (4-23), CHEC indicates no communication signal from the ECU for 3 seconds.

Leaves me thinking either dodgy ECU or dodgy ECU power supply - behaviour is exactly the same when the ECU is removed from the loom.

Can anyone help me with understanding how the ECU is powered - i.e. where the power comes from, what components are en route and which pin(s) should be receiving battery voltage when the ignition is on?

I have the wiring diagram from the manual, but some of it makes little sense to me unfortunately!

Or perhaps you have other ideas on where the fault may lie...

TIA!

Cheers,
Ian.

[KiwiCol]

Sounds like a job for Thomohawk, unfortunately he's a bit far away from you Ian, although there's always email.

[grog]

Have you tried your spare key?

[black14]

Yeah mate, spare unused from new key makes no difference.
From the manual, it's the ECU that initiates the communication via the antenna with the transponder in the key.
This happens when I plug my ECU into another bike, but not on my bike.
Also, if it was an immobiliser issue, I'd expect to see the FI light on and a C42 code.
Given displaying CHEC, there's no code in dealer mode...

[grog]

Could the key reader(antenna) be faulty. We get lots of them faulty on cars at work. No idea how youd test it.

[black14]

Key reader could be faulty, but if that was the issue would still expect the fuel pump to prime, or at least start momentarily as it does with the ECU in another bike...
I've no idea how to test that either...

[grog]

Just thinking,cars with crook key will start for a few seconds and stop. Cars with faulty reader just crank, dont attempt to start. Mercedes with faulty reader just do nothing. Could be a clue??

[black14]

But how to test? Immobiliser antenna from Mick Hone is $460, which is an expensive way to find out!
I've put feelers out for a 2nd hand one, no luck yet...

[grog]

Yeah Mate, need more info, dont trust my thoughts. I cant even see reader in wiring diagram.Wait until the Northern crew wake up, could be someone who knows. 🤞🏻🤞🏻

[seth]

There was a problem and recall on some k5's in the uk for the imobiliser ariel.

[Hooli]

There was a problem and recall on some k5's in the uk for the imobiliser ariel.

Ring a dealer & give them the reg, they'll know if it ever got done.

[Hooli]

I'd say the behaviour with your ECU in the other bike is correct, as far as I know insurance approved (as these will be)  immobilisers always cut the fuel pump & spark along with the starter circuit. Did you try the other ECU in your bike? I bet it'd do exactly the same as you saw there.

I'm not sure how close the key has to be to work, but I'd bet if you held the correct key right by the keyhole then things would work, unless the two keys interfere with each other. Wrapping the wrong key's black section in foil should shield it & prove if the ECU works as it'd only see the correct key.

I can't say I've ever heard of a ECU fail in anything, let alone these bikes. So I'd look elsewhere. I know on the early bikes the fuel pump has it's own contact in the ignition switch. I'd bet the switch is the same on later bikes as it bolts to the bottom of the lock so didn't need to be updated for the immobiliser fitment. I've known several older bikes where the fuel pump is intermittent due to the switch being full of snot & making poor contact, so that's my first guess. If the immobiliser is powered from the same contact the pump then it'd explain your bike's behaviour. There's another contact for the rest (indicators, horn etc) so it also makes sense with what you've got still working.

There's a write up somewhere I did on rebuilding the ignition switch, it's not difficult. Just fiddly with all the small bits. I'd be tempted to open the headlight, bridge the appropriate contacts in the loom's multiplugs so the bike is switched on, then try it with your key in the ignition (so the immobiliser sees it) & find out what happens.

Between those two ideas you should be able to prove if it's the ECU or the switch.

Oh, a last thought - swap the fuel pump relay with that other bike too, it might be dodgy.
I think I see CHEC if I forget to connect the loom under the tank, so I'd assume the relay not firing the pump would give the same fault condition to the ECU.

Last last thought... have you had the tank off to check things? the earth leads from the pump & fuel sender can rot (good old black wire corrosion) and fall apart. Mine still worked when it happened as it earthed through the tank, but I suspect it shouldn't have as the tank is rubber mounted. 12v to the right two wires in the 4-pin plug to the tank would prove the pump is working as a quick check.

Good luck.

[Andre]

 Rebuilding the ignition switch worked for me.

[black14]

Thanks guys!

I'll try the ignition bypass, but as I can see power at the Fuel Pump relay and the bike cranks over on the starter when turned on pretty sure it's not that. Swapping the Fuel Pump relay changes nothing. If I supply the earth to the Fuel Pump relay (that should be supplied by the ECU) the pump runs, so that discounts fuel pump earthing issues - but I'll check that anyway.

I'm not game to put someone else's ECU in my bike - if my ECU is fried there may be a fault on my bike that's caused that - and I wouldn't like to fry another one! I did try holding my key next to the antenna on the other bike, not with foil around the other key though - still said wrong code as per section 11-13 of the manual.

[seth]

Thanks guys!

I'll try the ignition bypass, but as I can see power at the Fuel Pump relay and the bike cranks over on the starter when turned on pretty sure it's not that. Swapping the Fuel Pump relay changes nothing. If I supply the earth to the Fuel Pump relay (that should be supplied by the ECU) the pump runs, so that discounts fuel pump earthing issues - but I'll check that anyway.

I'm not game to put someone else's ECU in my bike - if my ECU is fried there may be a fault on my bike that's caused that - and I wouldn't like to fry another one! I did try holding my key next to the antenna on the other bike, not with foil around the other key though - still said code as per section 11-13 of the manual.

To use a different key for the code of a different ECU, you need the imobiliser ariel to be well away from your own key or the ariel picks up both and gets very confused.
1 guy did manage to use a replacement lock/ignition but had the ariel and his ecu key down by the oil cooler to test everything.
Just out of interest the flasher relay hasnt been changed and has been tested as I'm sure that has to do with the power feed to the fuel pump when starting .