Right, having got over my annual period I have decided that selling the car may be a little hasty (if a mod could please lock, delete, burn, dismember that thread I would appreciate it).

 

Ok. So here are some symptoms and status. They may, or may not be associated to each other.

 

1. On cold start up, revs climb to 1300 after catching, then drop to approx 150, before picking back up and settling at 1000 ish. The rev drop will occur after each touch of the throttle until the car has been running for a few minutes (no accurate engine or coolant temp gauge).

 

2. Pressing the horn causes speedo needle to quickly swing 80mph above whatever it is currently at and then drop to previous speed. This occurs regardless of engine running or not.

 

3. Switching on dipped headlights (HIDs) causes speedo needle to quickly swing the full range of the speedo and then back to zero. If this action is repeated, the range of the swing decreases each time until it only jumps 10-15mph. This occurs regardless of engine running or not.

 

4. All fuses in place and correct. No corrosion found on any of the fuse/relay boxes.

5. Car is a JDM with a mph convertor fitted behind dash cluster.

6. Dash lights are dimmable and stay at whatever setting they have been set at.

 

 

I'm not the greatest automotive electrician. So any help is appreciated.

If people think it's an Earth fault or a short, some indication of how to go about finding it would be helpful as I ain't got a clue where to start.

Do you have a picture of how the gauges are wired for the MPH / KPH converter, might have a touching wire on something else.

Good point.

I'll have to take the cluster out and have a look. I'll put some pics up once it's out.

I would remove the mph convertor and see if your speedo problems go away. Your idle could be down to a faulty or blocked IACV and or incorrrect TPS/idle adjustment, does the car idle around 750rpm once up to temp?

Edited October 18, 201312 yr by Steams

Yeah, once up to temp idle settles to 750-770

Have a read of this mate, it may help; http://s95014253.onlinehome.us/63104/157335.html

Im sure I've read something similar caused by the mph converter. Try removing that first like has already been said.

It was literally as I was typing out the symptoms above that I remembered about the speedo convertor lol.

I'll see if I can get time tomorrow to get the cluster out.

Removed this little box of tricks

 

All the needle jumping has stopped. excellent.

Anyone recommend a reliable kmh-mph convertor?

 

Next stop is the idle vs wd40. Best get cracking.