Quick question for those who have relocated their battery..

[Jezza_hr]

Where did you find to be the best ground points in the boot?

Since relocating my battery and going back to my standard tachometer on my OMEX, I am seeing erratic readings when the battery is under load from ancillaries such as the indicators and electric windows. The needle jumps up and down without any change to the engine's idle itself.

Speaking with OMEX, they believe it is due to bad earths, but having gone over them and my battery now getting a steady 14.5v when the engine is in use, it appears the ground wires are in a good spot. But I want to ground the car even further to see if this solves the issue, but I'm trying to choose the best spots. Any ideas?

[jondee86]

Just to confirm... you are using an output from the OMEX to drive the
factory tacho via a pullup coil or similar ? Do you have a diagram of how
that is wired up/earthed ?

Cheers... jondee86

[Jezza_hr]

Yeah, I'm using one of Omex's own tacho signal converters. The signal wires are connecting at both ends corresponding to the ECU and the OEM tachometer. I have changed the power feed to the converter between a constant 12v feed directly from the battery, to an ignition feed sourced from the back of the stereo (the feed from the stereo works better). The signal converter is grounded on the centre console up next to the heater controls. I did ground it on the chassis next to the passenger foot well, but this made no difference.

[Motax]

I remember one of my friends had problems starting his car with the battery in the back. It's not that it did not start, but the starter was turning over quite slow, and it took a while for the engine to fire up. We then ran an extra ground cable from the battery to the engine. I'd give that a try, especially if you haven't experienced any problems before relocating the battery.

[Ivan141]

The centre console is pretty poorly grounded as far as I can remember. I prefer grounding to the chassis myself.

[Jezza_hr]

Motax Wrote:I remember one of my friends had problems starting his car with the battery in the back. It's not that it did not start, but the starter was turning over quite slow, and it took a while for the engine to fire up. We then ran an extra ground cable from the battery to the engine. I'd give that a try, especially if you haven't experienced any problems before relocating the battery.

I did this previously and it made no difference to the performance unfortunately. I may just have to get more cable and toy around until I see results.

[Ivan141]

Another idea you could try,
Wire the tach booster in near the ECU, and use an ECU power feed/ground, then run wire to cluster from there.
That way you can rule out signal interference between the ECU and the booster. The signal to the cluster is about 3x higher voltage, so less likely to catch any noise.

[Jezza_hr]

I'll look into that Ivan and see if it helps, thanks

Bizarrely, I sent a log over to OMEX for inspection today, to see if they could determine a problem. The only thing they could determine is that my engine seems to be running a little lean, but the smell of fuel would tell me otherwise.

[jondee86]

Four wires seems to indicate that the converter will have a coil and a
switching transistor inside. Use of the transistor suggests that the ECU
is using low level signals for switching, meaning that the converter to
ECU wire would be sensitive to EMI. Make sure that this wire is not
bundled with wires that carry switched loads from orther devices.

As suggested above, the earth wire from the converter should be
attached at (or very close to) the point at which the ECU earth wires
are attached to the engine.

Cheers... jondee86

[rene]

first you connect the 2 black 2,5mm^2 cabels from the OMEX loom to negative terminal on battery

( read the manual)

then remove the tacho box no need, fit the tacho wire from omex to the toyota tacho wire and it will run perfect

on a LHD car is it the yellow wire in the small loom the goes thru the bulk head near the brake fluid canister