Wierd, tacho reads while motor is not running?

[Qwrx]

Gday,

Having some troubles with a civic dash, only a couple of the lights are working. The tacho sits on 0 as you would expect when there is no power at all on, but as soon as the accesories power is on the tacho reads around 1000rpm??? then when the motor is started the tacho doesnt move from 1000rpm. This is causing headaches because the motor is going into limp home mode but we cant check the error codes because the CEL isnt working.

Has anyone seen anything like this before?

The car is an EG civic, its a freshly built rally car so we have had the entire dash and wiring out of the car.

Please help

Thanks

[hayashi_1986]

That's worrying :( Have you had a look at all the underdash fuses and relays? Or the fuses under the bonnet? Check every single one carefully. The reason why the CEL might not be working could be because of a blown ECU fuse. I'll won't completely rule out the ECU because it's pretty hard to blow an ECU. If it's still the stock ECU your running, then it's possibly malfunctioning. If it's an aftermarket standalone or piggyback which required you to splice a few wires, then that's where you may need to look. Plug n' Play, not so much of a problem I would imagine.

Otherwise, the wiring - once it was out of the car - was it touched or taken apart in any way? Any wires cut that were thought to be 'unnecessary'? If so, look back at the wires you've cut away with a wiring diagram and see whether any of the wires have to do with a sensor of some sort. I can't be very specific as I'm no auto elec., or a full blow Honda expert...but the next step, if it's still giving you grief, would be to take it to an auto elec. for a look.

Another thing you can try is to ground the car properly and see if that helps.

Let us know how you go!

Cheers
P.S.: Interesting :) Rally car...What model?

[bennjamin]

its getting the current @ off , that would usually be there @ 1,000rpms.

Something is amiss -bad ground somewhere

[Qwrx]

Its an EG civic, one of 3 in the team. Although one was rolled on the weekend during rally of canberra. The problems turned out to be a plug that had somehow vanished deep into the wiring loom, and then the distributor.

[vippy84]

that is wiring problem..
i had this problem when installing the the water temp gauge... and we did the wiring wrongly and the reading for both were wrong.. it cant be fuses..

good luck

[EGJOE]

Hey buddy
Check all the ground wires normally the culprit:thumbsup:

EGJOE