[Barbs]

Hi all

I am wondering if anyone can help with this issue.

Hyundai Model i30
Year 2011
Engine1.6
Fuel Diesel

After sometime driving my speedometer starts to fluctuate +/- anything between 5-20 miles.

This occurred not long after I fitted an after market head unit, where i made the mistake of nicking two wires with a small blade which cause the brake light fuse to go, which stopped the car from shifting gears (which is fair enough as it is a safety feature). the wires did not get severed but rather the cable sheathing cut.

Cables taped up with electrical tape.
Brake light fuse replaced, break lights working car shifts drives as normal.

So the car needed new break pads all around and new break disks on the front and front suspension shafts to be replaced, all happened today.

As i drove the car to the garage it was fine, then from garage to work place also fine.

From work to home 20 mins in and speedometer starts to fluctuate.

Got home and did a bit google and read about input and out put speed sensors and though maybe i damaged them when i nicked the cables.

The head unit i installed is an android unit and can work an ODB2 Bluetooth adaptor, where i can read all sorts of data from the ECU including speed.

I Used the App torque to display 2 digital speedometers one reading data off the ECU (should be very accurate) and one using GPS data to estimate speed.

I did this to make sure that the ECU is reporting correct speed and to have something to compare to the speedometer.

So I went out for a drive and everything was working as you would expect. however 15-20mins into driving the speedometer started fluctuating, but the ECU read out on app did not, and was more or less the same as GPS speed read out.

So here are my questions:

1) Are the speed readouts from the ECU the same as the speedometer (as in the same source).
2) can the speedometer be damaged? or some other sensor?
3) Could taped up cables cause as issue like this?


Also the speedometer sits at zero when not moving.


I would really appropriate any help and advice I can get.



Thank in advance. 

[nzenigma]

Basically its #3 Plus.

Also known in the trade as finger trouble.

Work back and find what you did wrong.
ECU will rely on output data from sensors on the transmission.
Usually the data line goes directly to the speedo.

[Paolo39]

I do not know what exactly i30 speedometer is build, but I know that stepping motors in instrument cluster can go bust. Maybe because you make a short.
Someone with good scan tool (Snap On) could test instrument cluster (if available for i30)

[Barbs]

Thanks for the reply

I took all the tape off and stuck my phone in there and took a picture as the cuts are deep inside the dash. and it looks like one wire is in worse condition than the others (see picture)

The yellow wire sheathing seems to be cut, however the black wire looks bad.

can I repair that by cutting the effect wire and adding a joining section?

its quite tight in there and I am not super comfortable using a soldering, can I use wire crimps instead and cover it with heat shrink?

Assuming the instrument cluster is effected, can I replace it with another one in the form of plug and play? Or will a need it to coded by a dealer?

Thanks again

[Paolo39]

There are some butt connectors available, which contain solder and heat shrink. Ideal for repairing damaged wires.
NTE Electronics Heat Shrink Self-Solder Butt Splice Connectors - YouTube

[Shambles]

There are some butt connectors available, which contain solder and heat shrink

Can't see those being much use for wires in a tight harness

[Barbs]

oh that is cool, did not know something like that existed.

I don't think i can use them with my particular issue. but I will make use of such a thing in the future I am sure.

I will probably use normal ones.

Thanks.

[nzenigma]

when I said 3 finger trouble, I was meaning to go back over everything you have done, or problem likely to have been caused.

[tw2005]

There are some butt connectors available, which contain solder and heat shrink. Ideal for repairing damaged wires.
NTE Electronics Heat Shrink Self-Solder Butt Splice Connectors - YouTube

I'd run with those joiners as well. I've used them and work very well. If you have to unbind the harness wrap a bit to get it done , so be it and then tape it back up.

[tw2005]

Also vehicle speed sensor  data is also fed to the OEM Head Unit at pin 9 of a 16 pin square conector at the rear  M54A is the connector label. If the schematics are correct it's a green cable, orange trace

[Barbs]

OK so Friday I bought some crimps and a crimping tool, I cut the damaged wires and used section of new wire and crimps to fix it, Covered everything with electrical tape probably a bit excessively.

I drove around 200 miles over multiple trips and this issue seems to be gone and speedometer readings match the reading over OBEII and GPS reading.

also while in the store i came across those fancy heat shrinking crimp with solder, I bought 2 pack of 30 and plan on using them in building an arcade machine, used one of them in a test and it is like magic.

so i want to thank you all for your wisdom and advice as well as your time

[Dazzler]

Great result. Thanks for the follow-up post.