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Author: Subject: Speedo / Rev Counter issues?
Smoot

posted on 21/2/19 at 08:04 PM Reply With Quote
Speedo / Rev Counter issues?

Evening all,

Finally having some time to getting around to working on the MK I bought a year (or 2) ago!

Ever since I got it, the speedo has seemed to lag a little behind the actual speed, i.e. after speeding up to 60, the need would rise a few seconds later and sit at 60, and slowing down to 40, the needle would drop a few seconds later - not sure if this is normal? or to be expected?

The speedo is one of the 'ETB Instruments' ones:



This all started because I wanted to add shift lights (or a rev counter of sorts) as the car currently does not have either of these. It did have shift lights fitted by a previous owner, but were removed for some reason.

I took the dash of for a closer look, wiring seems a little messy... I guess my question here is, how do I Identify which wires will be the ones I need to use if I have a rev counter/shift lights? Is there an easy way to tell? I am assuming they are still in there as there are quite a few random ones just hanging behind the dash at the moment.

Regarding the speedo - I checked the wiring diagram located on their website:

https://etbinstruments.com/image/data/SPEED_MK3_340002_1a44_D.pdf

I have identified the cables which would head to the sensor, would the way they have been arranged/spliced affect the performance of the speedo?

White and red are the two cables going in to the blue twinned cable, the black heatsink seems to be an earth.



I haven't been able to follow this cable yet, it goes into the tunnel, and I guess towards the sensor which is .. on the differential? Is there a chance that could be out of alignment/having issues?

Thanks in advance for your help on either of these questions!

Richard





Very little experience, but lots of effort and ambition to learn!

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melly-g

posted on 21/2/19 at 08:20 PM Reply With Quote
I can't answer your question but that looks really dodgy to me!
I think I would have that all out and sort it properly!

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Smoot

posted on 21/2/19 at 08:27 PM Reply With Quote
quote:
Originally posted by melly-g
I can't answer your question but that looks really dodgy to me!
I think I would have that all out and sort it properly!


I am tempted to.... Once I get this sorted, and know what everything is/does, clean, rewire what is needed and possibly redo the dash in a much nicer configuration - but right now it is about getting it working first





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miskit

posted on 21/2/19 at 08:51 PM Reply With Quote
Pretty sure the black heat shrink is taking the cable shielding to E. This is a good thing as it prevents interference.
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Bigboystoys

posted on 22/2/19 at 03:46 AM Reply With Quote
The number of magnets you are using at your pick up end will also affect how quickly your speedo responds, sounds to me like you just have one magnet.
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rf900rush

posted on 22/2/19 at 07:03 AM Reply With Quote
I had an ETB speedo on may DAX.
Mine car accelerated faster than the speedo.
I don't know if ETB are still around , if they are, Speak to them.
I suspect that they were not designed with these cars being so fast.

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Smoot

posted on 22/2/19 at 09:34 AM Reply With Quote
quote:
Originally posted by miskit
Pretty sure the black heat shrink is taking the cable shielding to E. This is a good thing as it prevents interference.


Yeah I traced the heatshrink to an earth on the frame - is this wiring on though? Could the way it has been done affect the performance?

Thanks for the learn about the magnets. The wiring diagram is quite specific about distance and angle etc - possibly a very simple question but where exactly IS the pickup?

The ETB gauge being slow to pickup is good to hear that I’m not the only one with such an issue. Could I possibly do 2 birds with 1 stone here and change the gauge to a different model that has both speedo and rev counter functionality?

Thanks
Richard





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Bigboystoys

posted on 22/2/19 at 09:54 AM Reply With Quote
At a guess you will find the pickup around the rear diff area, either on propshaft input adaptor or drive shaft adaptors? Just follow the cable from the speedo back
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mcerd1

posted on 22/2/19 at 11:17 AM Reply With Quote
ETB are still around and they guys a pretty helpful too:
https://www.etbinstruments.com/


its worth mentioning that they no longer recommend using the magnet+reed switch type sensors -- instead they use hall effect sensors reading off a toothed wheel or the driveshaft bolt heads

(if you change the sensor its worth noting that the 4 ford prop shaft bolts aren't on an even pattern, so these probably aren't the best place to get a signal )





-

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ian locostzx9rc2

posted on 22/2/19 at 03:46 PM Reply With Quote
The guys are at etb are brilliant it may only have one magnet as said works better with 2 I’ve had etb gauges and they have been very reliable I think I’ve had that problem in the past and it was because it lost a magnet .wiring doesn’t look pretty

[Edited on 22/2/19 by ian locostzx9rc2]

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Schrodinger

posted on 23/2/19 at 10:45 AM Reply With Quote
The pick up could be on the diff, near the prop shaft or even picking up from the gear box using an adapter.





Keith
Aviemore

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Smoot

posted on 5/3/19 at 10:50 AM Reply With Quote
Thank you guys for your help so far on this, I haven't had a lot of time recently to check this out, but whilst changing oil/coolant this weekend, I had a quick look at the wiring again.

Regarding the rev counter (or lack of...) I found a few random wires (labelled in the 'instruments' group) that were not connected. most of these read 14.4v when the car was idling, but one of them (seen below on idle) read between 12.66-12.68 when idling.



When revving the car (no idea how much really) the voltage increased, and then decreased when the throttle was reduced



I had a quick look on Amazon to see how much a cheap Rev Counter would be to test this out, and most of them seem to work on just a few wires, positive, negative, signal, and dash lights occasionally. cheap example of one on amazon

Before I invest though, am I right in assuming this wire with the variable voltage on throttle is the correct wire to use?

I will have to strip back the tunnel carpetting to see where the speedo cable goes - as I still couldn't see anywhere obvious for that sadly!

Thanks
Richard





Very little experience, but lots of effort and ambition to learn!

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rusty nuts

posted on 5/3/19 at 11:17 AM Reply With Quote
There is no speedo cable as such, it will be wired to sensor likely on the prop or diff. Have you looked at a wiring diagram for the tachometer?
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Smoot

posted on 5/3/19 at 12:47 PM Reply With Quote
Sorry, by "speedo cable" I meant that cable yeah - I haven't had the time to trace it from the speedo back to the prop/diff where the sensor is located (it goes into the tunnel and that is currently carpetted up quite well)


Regarding the wiring of the techometer - taken from the website of that specific model:



http://www.offroaders.com/tech/images/autogage2_small.jpg

I guess I am wondering, is that cable I found which varies voltage based on throttle the green wire identified in the diagram above i.e. does the Ignition negative wire have variable voltage on throttle?

Thanks,
Richard

[Edited on 5/3/19 by Smoot]





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ian locostzx9rc2

posted on 5/3/19 at 07:24 PM Reply With Quote
You can get the wiring diagrams on etb instruments web site which may help you
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rusty nuts

posted on 5/3/19 at 07:59 PM Reply With Quote
What engine do you have? What type of ignition system? If you have a single coil check for continuity between the coil neg terminal and the tacho ,
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