speedo jumping

[sideshowbob]

I have a prefacelift ej9 which I put a d15b in running a p08 ecu thing ran fine just a bit smokey so few weeks ago I changed it for a non smokey d16z6 still had it running on the p08, got a p28 for it so changed it, lights were pulsing and speedo was jumpimng about, changed it back to the p08 and its just the same, vtec don't come in either. I've looked about the forums to try solve this but all I can find is people saying its fuse 15 in the interior fuse box the alternator fuse I've checked this abd its fine, what else could be causing this? Thanks

 

[TurboMirage]

bad grounds?

 

[civicious]

Vss.

 

[sideshowbob]

Checked the grounds they're all fine also tried changine the speed sensor in the gearbox. Had a multimeter on the battery and the alternator, was reading that the alternator was only charging at 12v so changed that and its still reading the same so after eveything there's no difference. When the p28 was plugged in it was only for a few mins but there was a slight smell of burning in the car, I noticed I could still smell this of the ecu so I opend in up and component q31 is a bit burnt and melted. Could any one put me in the right direction with this?

 

[jeremiahm]

Look at where the wiring harness goes around the intake manifold bracket next to the oil filter. That bracket rubs the harness there and causes a short that make your speedo jump, and ultimately go completely dead. It should be a yellow and black wire, if I remember right. You'll ultimately burn out a fuse, but I can't remembe which fuse blows.