Speedo cable causing car cut out in 85 4runner with Commo V6

[dawg runner]

Hi,

Got what i think is a weird one but it may be something simple as i have never seen or heard of it before.

Ater i got the speedo cable lengthened due to DUAL transfer cases, when i first put the cable back in the speedo was not working at all. When i was fiddling around with the speedo cable under the car i thought i had got the cable made to long and it was binding up. Eventually I proved this theory wrong by getting a drill and putting it at the same angle the cable would have been on and bingo the speedo started working behind the dash, but at the same time when i did this the car conked out. I had car running because as i said before i thought it was binding up so i was in and out of driveway trying different variations of the route the cable was taking to see if that helped. At the time i did not think anything of the conk out or at least that it would have anything to do with a mechanical speedo cable?????

Eventually i worked out the reason why speedo was not working was the cable was not being turned by the gear on the back of the transfer case as it was shagged to buggery. So i replaced this and put the cable back in and when i get moving above a couple of kph the car would conk out again, but you could stop and it would start straight away. I thought straight away i just wonder if that conk out that i had the other day when i was fiddling with cable has anything to do with this. I got under the car and disconnected speedo cable from transfer case and started car again. All it took was one 1/4 turn on the cable with my fingers and it stopped the car. Started it again and turned cable a 1/4 turn and it conked out again.

So the reason my speedo was not working was due to the gear on back of transfer case and now that i have the gear working again it turns the cable and the car cuts out....

Now i am thinking something shorting out in the instrument cluster but i thought i would ask to see if anyone has had this problem or something similar before.

I hope it makes sense.

Cheers for your help.

Dave

[GeneralFubashi]

Ignition wire somehow shorting to the speedo and grounding through the gearbox? Thats one interesting problem! Time to get the multimeter out and check the voltage at the speedo, or ground it to the body manually to see if its the same trick.

Very unusual to have this happen though.

[-Scott-]

Or ignition earthing through the speedo cable, and being interrupted by the quarter turn?

[RAY185]

Dont these things have to run a Vehicle Speed Sensor that sends a signal to the ECU? Sounds like you might have a problem in this area. Maybe someone who has experience with v6 commodore swaps might be able to give you info on how to check.

[dawg runner]

Woo Hoo!!! I fixed it.

After alot of investigation i traced it back to 1 plug on the instrument cluster. With it plugged in ignition would cut when car moved and unplugged it wouldn't. I had used a 12v ignition power supply in the engine bay that would work fine without instrument cluster plugged in but once i plugged the instrument cluster in and moved the car the instrument cluster would cease power to the wire i had used to power my ECU, BCM & Fuel pump. Not sure why it would cut out but i am sure there is a reason there somewhere. Changed the power source and booo ya.

I found it by removing the fuse that was inline before the pwr for the ECU, BCM and Fuel and put these 3 things straight to constant power. started car and rotated the speedo cable and no problem.

You know when i started fiddling with cars i HATED Auto electrics but i think very slowly starting to get the nack for fixing these little problems and now quite enjoy the challenge. OK i know i took the power supply from the wrong place to start with but if you dont make a mistake you will never learn.

I hate trying to explain these things. I know it in my head. Hope it makes some sense.

Cheers for the input guys.

HAve a good one.

Dave