Fuel pump still no go, 09 TRX420FPA

[Topendcol]

First issue was fuel pump wont start once ignition has been turned on. Replaced the pump as I had one on hand, than noticed no power so replaced the fuel pump relay as that was were i traced the power to. Still nothing so further inspection looks like signal is coming from the PCM (FLR B20) but not switching the the brown wire to the fuel pump. Ive checked the operation of the bank angle sensor and it appears operational. Fuses and wiring all appear OK. The engine stop relay also tests OK. Ive been through the repair manual and diagrams but to no avail. Fully stumped, any tips would be helpful. Thanks

Col

[Mech]

You say it has power to the relay, but are you sure the relay has an earth as well ?

You say the fuses and wiring appear ok, but have you tested the fuse and wires for continuity with an ohm gauge ?

Wires sometimes break inside their insulation just right where they come out of the crimped metal terminals in multi-plugs. If you use long nosed pliers and try bending each wire, one at a time, you sometimes find one that's too flexible because it's only the insulation you are bending.. the copper is broken.

If the relay is getting power and earth, then you should check it's contacts are making good contact with the continuity tester of your gauge. If the relay is working and the contacts are good then presumably it has to be in the power feed wires to and from the relay. You could unplug the relay and jump the power wire terminals to feed power straight down to the pump. That confirms the fuse, wires and pump are all working .. or not. Then you concentrate on the relay's control circuit.

And.. when testing for power it's better to use a test light rather than a multi-meter. The multi-meter needs so little power that it can show a voltage even with a dirty contact that won't let enough power through to run a light or pump. That can make us think there's power when there isn't really. If using a gauge you really need to do a "voltage drop test" when the circuit is under load. Using a gauge to check for voltage is often a deceptive trap..

 

[Topendcol]

Thanks Mech

Ive been testing with a new LED test pen, I think i should try dig up my old globe style test pen, definitely makes more sense. Was under the assumption it's working because with the relay removed the power lines for the coil/inj/pump junction connector are dead but active when installed. But cant get the switch wire for the pump to work even with the control wire switched. But as you mentioned, could be getting a faulty reading on the control wire.

As for the earth, I'm not sure there is any earths on this relay, doesn't appear to be on the wiring diagram. May be some sort of inductive switching but I'm not sure. Will try the bypass method, that was my next go to. 

Hoping it is something simple as a broken wire, I cant start the bike or even change gears on the Auto shift, just get the flashing '-' were the 'N' is meant to be. So up sh** creek ATM. Ive also replaced the combination meter but that didn't work. The old display was unreadable anyways so needed replacing. Just seems like Im missing something. I'll keep pursuing.  

Do you know if the PCM (main computer) switches the earth or does it send a positive output. Does appear on second looks at the diagram that it completes the earth circuit. I may have been looking at this the wrong angle. If thats the case the PCM may be corrupt. But will check all bases first, could imagine those wont be cheap. 

 

[Topendcol]

Checked the ground signal for the fuel pump, no continuity to ground. Bypassed the ground signal and earthed to the relay, the pump runs. 

Checked the main earth continuity to the PCM, all good. 

Went through the service manual again, done the serial communication line tests and the PCM power/ground line tests. All roads lead to replacing the PCM .

Had suspicions but its good to be 100% sure.

[Mech]

Ok.. Progress.

And yeah, things that switch by turning the earths off instead of the power can catch us out. Bad earths can catch us out.

Can you bypass/jump the pcm to see if the circuits work then ? Always best to be sure parts are the problem, and the only problem, before condemning them.

Edited January 7, 2024 by Mech

[Mech]

And that gear indicator sign combined with the no start the manual does say is either the PCM or power supply or earth. I'd always try to bypass/substitute the PCM to be real sure that was going to cure the problem.. But I'm a mech and have to be sure.. and parts are dearer here in New Zealand.

[Topendcol]

Not much cheaper over the ditch in Oz. Especially with the dollar rate to US. 

Not to sure which way to go about it (PCM BYPASS) but done the ground control wire bypass for the fuel pump and it seemed to work.

Not looking forward to spending $600 for PCM and it wont work fix it, cant see any other options ATM. Ran both PCM tests and they both indicated it was faulty. Hopefully it'll get her running again.

Then need to work on the power steering and auto shift.  

The power-steering has never really worked, and in the owners manual it mentions that prolonged outage may cause damage to the system.

I recently done the steering reset to clear the DLC fault but didn't fix the issue. The PS light is still illuminated on the combo meter. No other DLC faults come up on the meter.

So was gunna pull out the shift control motor and hard wire it for testing. Also seen online people pulling out the shift motor housing/gearing, cleaning it and re-greasing. Probably purchase shift angle sensor and replace as well. Had issues for a few years now with the auto shift, once the quad runs for an hour or so the '-' indicator comes on and wont let ya shift. Have to let it cool down and go again.  

Not sure if its all related but even if the power steering and shift motor are faulty, the bike should be able to start regardless. So makes me think the PCM is the most likely issue (for now).

Thanks for getting back to me, I know it all takes time and I appreciate your efforts. 

PS.... My old man is Kiwi, and his two mates are A grade Mechanics as well. Must be something over there to create great Mechs. Cheers 

[Mech]

End of the world Mate..  We have to keep things going.

About the only other thing is.. check all the earths.. As a general rule, when a whole lot of things go bad it's often all because of one fault, and one thing lots of systems have in common is earths. And I'd try bypassing the PCM with a some hunks of wire. If you've got the manual it will tell you which pins are for what in the text part somewhere I think..,  I think they have two or three relays and one or two circuit breakers.

Unless.. you can borrow one, or take your one to a bike shop and ask them if they would slip it into a bike.. Or confirm it's crook..

I'll have a look through the wiring diagram tomorrow and see if I can see any other common connections and which pins are which in the PCM..  It sounds like you've read it pretty well though so don't hold too much hope in that.

The shift you should be able to operate manually and that's the first test, then you try the buttons, and then you suspect the control module.. The manual describes how to test it all but it's a mighty long process of elimination.. I'll have a refresher read of that too.

[Mech]

Ok, so it's not the conventional manual/electric shift I though it was. It's the hydraulic auto. And the PCM isn't the one I was thinking of either. My bad jumping to conclusions without checking.

So I had a read and it looks like you need to ignore the PS until the engine is running. The PS, gear shift and engine control/start though might both have a common cause. In every section I read it kept saying the same things. Check all the power supplies to all of the control units and the actuators, and check all the earths to all those same things. Then the next thing apart from the actual PCM being crook, or the dash being crook, is the communication between them.

Looking at the systems individually it should be fairly easy to check the crank position sensor, the injectors have switching power, that power is getting to the coil, and it's peak voltage, and the fuel pump is running and got pressure. For testing things that only have very momentary pulses, such as the injectors and the crank position sensor it's best to use an old fashioned analogue gauge with a needle. The needle will flicker with a momentary pulse where the multi-meter with it's slow count can very easily miss a pulse.

The transmission. The gear position and angle change switches are both suspects if all the power supplies and earths are good. The switch tests are a bit complicated but can be done with a multimeter.

But in every case it keeps saying.. power and earths. On cars and trucks when we get a whole bunch of problems, it's often all caused by a bad power or earth, and they can sometimes set trouble codes, and often they do not set codes.

The manuals mostly do tell us everything we need to diagnose problems, and in that manual it mentions the conditions under which lights and indicators flash or don't flash, and codes get set or don't get set, but without being there checking all the combinations of conditions and symptoms It's a bit beyond me to figure. If you read each section though, right through, going back several times if necessary as you start to understand the interconnections between systems, you'll probably eventually realise which lights and indicators are behaving normally in staying on or flashing, but not actually meaning there is a faulty part in that system.

Concentrate on getting the engine going, then the other systems can be tested, but keep those other systems in mind as you look at the engine problems, they are likely all connected.

Good luck with the reading and the checking. Let me know anything interesting you find and I'll have another read and hopefully we'll be able to get this thing fixed without a PCM, or, at least be confident it is the PCM before splashing out..

[Topendcol]

Hey Mech, Long time.

Took bike to mechanics to confirm PCM, only charged us $150. 

Ordered PCM, $900 AUD wasn't an easy purchase but plugged it in and she worked no worries. The gear shift isn't playing up either so it might be related to the PCM.

Side note, I found the cheapest PCM in NZ, but they wouldn't ship to AUS. The US PCM had one different letter in the part # so i didn't want to take the risk, would of saved $250 but didn't want to risk it. 

Thanks for your help, and without this platform and the service manual it would of cost a sh** load more. 

 

[Mech]

Ok. Glad to hear you got it going. Glad it cured all the problems.

$150 to plug in some other customers PCM ? Sounds about right.. Why we need to do things our selves.

I would have shipped it to you if you'd got it sent to me. Yell out if there's another time.

And yeah, this is a good forum. Having the manuals is a big help, friendly people, no pedantic dribble, good mods.. One of the best.