Electrical bugbear in a VN BT1 304

[savage1987]

Wired in a L3 cluster recently from a VN V6, switched a V8 tacho into the L3 so it should all be OK.

Trouble is, the instant fuel readout is erratic. Sometimes it reads about right, and will do so for a while, but a lot of the time it reads 1L/100km or less, or anywhere in between (NEVER over the real figure). I'm positive this is a problem with the wiring somewhere but I've sussed out the yellow/black wire to the loom near the ECU and it doesn't seem to be suffering anywhere..

Possibly related problems that are super annoying:

• boot light stays on all the time
• torque converter doesn't seem to EVER lock up.. this could be an ECU problem or something else I haven't forseen..
• some other earth cables have been found dodgy already .. starter loom main earth being the biggest problem. that's fixed now.

any suggestions appreciated, I don't really know where to start.

thanks
sam

[APV_Special_Vehicles]

Give me a call and explain a bit more. Please
I might be able to shed some light ????
Richard 0430033821
APV 03 8740 3720

[savage1987]

Might just do that tomorrow after work if I get a spare minute

thanks
sam

[savage1987]

I think the inst. fuel problem is somewhere behind the stereo head unit.. the unit isn't mounted properly yet and is therefore free to move a bit (don't have 90deg RCAs yet so doesn't fit) and I think its movement may somehow be impacting on the inst fuel wiring?

make sense?
annoying problem, will be glad to see the back of it

[Warranty Void]

There is a good chance that you are getting some back feed through the reversing light circuit. This would possibly affect the behavior of the lock up converter. Check the trailer plug wiring or remove trailer plug wiring, also rear clusters play up like mad with poor connections and can affect the dash module believe it or not. I had a wildly fluctuating speedo and a malfunctioning odometer from this. You should unplug the rear cluster and trailer looms yo see if there is any difference. Alternately pull all the fuses that aren't essential and see if there is any change, put them back one at a time to find your culprit.

[88GreenVN]

The ECU is sus by the look of it. Not locking up is a sure sign of a dieing ECU.

The yellow black goes to the engine loom connector at A2. The plug is up under the glove box more so than next to the ECU.

[savage1987]

Switched for another ECU today, still no lockup.

Maybe I tapped the wrong yellow/black wire .. ? I T'd onto one about an inch from one of the two ECU plugs. Seems like the correct feed though, it reads zero at the correct times on deceleration etc and reads well most of the time (worked 90% of the time today) just sometimes goes totally spastic. I did have another quick look for that connector today near the glove box but couldn't find it.... again.


I will sus out if there is a trailer plug; I don't think there is. I'll also have a look at those tail light looms, pretty sure they are quite fuxored.

[88GreenVN]

Switched for another ECU today, still no lockup.

Maybe I tapped the wrong yellow/black wire .. ? I T'd onto one about an inch from one of the two ECU plugs. Seems like the correct feed though, it reads zero at the correct times on deceleration etc and reads well most of the time (worked 90% of the time today) just sometimes goes totally spastic. I did have another quick look for that connector today near the glove box but couldn't find it.... again.


I will sus out if there is a trailer plug; I don't think there is. I'll also have a look at those tail light looms, pretty sure they are quite fuxored.

You almost apsalooootlyyyy have the wrong yellow black...

[savage1987]

shit, I will try to find the right bloody wire today. I don't know what I'm looking for really though no idea. Does it come through from the big firewall grommet? I'll start looking around there.