Rev 3 turbo Speedo intermittant

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MR2madlad
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Rev 3 turbo Speedo intermittant

Post by MR2madlad » 11/08/19 21:14

Hi

I've a tubby that has an intermittent speedo that's driving me crazy.

At high speed 4o MPH+ the check engine orange light comes on so the ECU, power steering ECU also is not detecting the pulses.

Looking at the wiring diagram I had trouble finding for this car the sender talks to speedo, the speedo talks to ECU / Power steering ECU so if speedo is fault that could be the issue as could be the KPH to MPH converter as its before the speedo.

things I have checked so far:

Pulled electronic sender out gearbox, gear on end is ok, and so is the one on the diff.

I have fitted an new electronic bit to the lump in the gearbox with a brand new connector off a Celica funny enough, as the original the 3 pins were well rusted as was the original loom plug, all soldered together and heat srunk.

Continuity tested +12 power from ECU fuse (accorging to wiring diagram it gets power via ECU fuse) in engine bay to +12v on loom plug, same with GND to chassis all 0.2 Ohms, even wiggled and pulled the cables.
Continuity tested the signal out from loom plug to the loom plug next to ECU in boot, yellow wire with red strip enters connector in boot and then turns on the other half of the connector to purple with silver dots.

Continuity tested connector in boot in to out, ok and from boot connector to the connector in passenger foot well left panel, 0.2 ohms all good, continuity tested loom from passenger foot well to back of instrument cluster where the KPM to MPH converter is, again 0.2 Ohms so the cabling is good.

In loom down in passenger foot well I stripped a section of the Purple with silver dots wire and have wired an LED with 1k Resistor from this wire to GND and taken it out for a drive, the LED flashed in relation to speed so I now totally know the sender in box is good and working, i.e slow flashing at slower speed, fast flashing / looks fully on at high speeds.

I've stripped the speedo unit out of the cluster and replaced the 3 electrolytic capacitors on this, 2 absolutely stunk of fish when de-soldering and legs were green so they were past their best and had leaked, I re-soldered everything on the speedo board as some joints also looked suspect, cleaned and reassembled.

It worked for about 10 mins and is now back to not, it does this at random, some days it works fine other it works then fails, and never works then surprisingly springs into life, LED was pulsing away happily throu out so sender is still outputting fine.

I think either the KPH to MPH converter is dead or the speedo unit its self has an intermittent IC on it.

Has anyone out there had trouble with converter thing before?

Next port of call it to connect LED to output of converter and see if its this that's intermittent of the speedo gauge.

Would be interested to know if the speedo gauge actually fails if anyone has had this?

Thanks




Absu
Posts: 76
Joined: 21/06/19 21:46

Re: Rev 3 turbo Speedo intermittant

Post by Absu » 13/08/19 23:49

MR2madlad wrote:
11/08/19 21:14


I think either the KPH to MPH converter is dead or the speedo unit its self has an intermittent IC on it.

Has anyone out there had trouble with converter thing before?

Why don't you remove speedo convertor and connect all wires back together and see if sort out the problem.

Some convertors are crap..especially the one with small square black box and a few wires.


Topic author
MR2madlad
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Re: Rev 3 turbo Speedo intermittant

Post by MR2madlad » 17/08/19 20:39

Absu wrote:
13/08/19 23:49
MR2madlad wrote:
11/08/19 21:14


I think either the KPH to MPH converter is dead or the speedo unit its self has an intermittent IC on it.

Has anyone out there had trouble with converter thing before?

Why don't you remove speedo convertor and connect all wires back together and see if sort out the problem.

Some convertors are crap..especially the one with small square black box and a few wires.
I've done the above today and the speedo is working put the converter back in and it stopped so its the converter that is the problem.

Looking online they are £55 for the same one I have which is a small square black block with 6 wires coming out however 2 of the wires (red and green) are in parallel internally.

Currently I have no idea what speed I'm truly doing as the face of the speedo was changed when the converter was put in, just down the road from my house the council have put up a speed radar display thing that tells you your speed but without the possible fine.

Looks like 45 ish shown on MPH gauge scale is actually now 30MPH according to the speed radar readout so the kmh scale is totally out as well but at least I know roughly where 30 MPH is not ideal.

As the converter for what it is, is bloody expensive for a cheap Chinese chunk of junk I am looking to maybe get a UK 160 MPH gauge from a scrap car and fit this into my cluster and set the mileage numbers to what mine currently reads (easy to do just push metal bar up and wind numbers round and push bar back down) but here lies a problem.

Will the UK speedo de-limit the 112 MPH?

From what I could find the black electronic sender on the rear of the gearbox is the same part number on both jap and UK cars (this make sense as the replacement I fitted came from a UK R reg Celica) so its not the sender that makes the difference it looks to be the actual speedo gauge.

I can get a UK 160 MPH speedo gauge for £20 thus saving £35 hence the question.

Anyone done this?

Thanks


Absu
Posts: 76
Joined: 21/06/19 21:46

Re: Rev 3 turbo Speedo intermittant

Post by Absu » 17/08/19 21:27

I don't know if UK speedo will delimit to be honest as I never replaced one.

Buy a good one and is not expensive. I've been buying speedo converters here ;http://www.ncs-systems.com/car-electron ... basic.html since 2005 for many cars like Soarers,Supras.. MR2's and I fitted to mine about 6 moth ago as mine is Jap import and I fed up with speed cut. It comes pre programmed and automatically de-limit 112 MPH speed cut. Comes as well with instruction and wiring fitment..easy to install just at the back of instrument cluster, Also will not affect electric power steering ..like HKS SLD

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Re: Rev 3 turbo Speedo intermittant

Post by SonicSW20 » 18/08/19 12:32

UK speedometer will not delimit.
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