electric speedo drive testing

gelmonkey · Post by **gelmonkey** » Mon Sep 26, 2011 11:25 am

Mrs Gelmonkey is going to help me sort out a link to the Autometer website later so that you can see for yourselves the wiring diagram.
As I am only used to chucking fibreglass about i am seriously lacking in computer skills.
I have sent an e mail to Autometer to see if they can shed any light on this for me aswell.

Thanks again for your help with this.
Hopefully it will be sorted soon

cheers
P

DaveEFI · Post by **DaveEFI** » Mon Sep 26, 2011 11:59 am

The doc Ramon sent me shows the sensor to be active - it has a couple of transistors inside it. So it would need the 12v supply to work, which is why a DVM doesn't show an output.

I'd try wiring the sensor to the 12 volt supply as Rover does it, but with a 1k ohm resistor to ground on the other leg, and take the output to the speedo off the 'top' of that resistor. If that doesn't make sense I'll post a proper circuit.

gelmonkey · Post by **gelmonkey** » Mon Sep 26, 2011 2:58 pm

Hi Again
I have had a reply from Autometer and this is what they are saying...

Paul,

A couple important things. First of all, if it’s a 3 wire sensor, it requires 12 volts to the sender. If it’s a 2 wire, it does not use 12 volts. Second, the speedometer does not have to be calibrated to work. Upon proper installation, the speedometer should work; it will likely just be inaccurate until it’s calibrated. Therefore, focus on just getting the speedometer to operate before calibrating it.

From our experience the number one issue with speedometer not operating is an insufficient ground. The speedometer can power up with a sufficient 12 volt ground reference, but there also be a ground reference for the signal. This can be accomplished by making sure the sender is grounded to the engine and the speedometer is grounded to the engine. This is an engine ground, not chassis, or battery negative ground. It’s important that it is the engine.

Yes, as a last resort you are welcome to send the sender and speedometer back to us.

Thank you,
Matt

So will try this tonight but will also post up the info as mentioned in a previous post today.

cheers
P

minorv8 · Post by **minorv8** » Mon Sep 26, 2011 5:40 pm

I also have a Automweter speedo and LT77 box. Since my box is from TR7 it had mechanical sender. I turned an adapter and used the TR7 gear (pinion ?) and coupled these to an Autometer sender. Works quite nice. At least these are compatible items.

gelmonkey · Post by **gelmonkey** » Mon Sep 26, 2011 6:04 pm

Hi Minor
That is really interesting and may be a route I have to look into.
What i cant get my head around is the fact that Muscle Manta had no problems at all with his set up!

Probably have too many fibreglass fumes in my brain to see or think clearly
Thank you for the info though.

cheers
P

gelmonkey · Post by **gelmonkey** » Mon Sep 26, 2011 6:15 pm

Hi Guys
Here is the wiring diagram and all the relevant info.....

http://www.autometer.com/productPDF/1140.pdf

Thanks and see what you think

cheers
P

DaveEFI · Post by **DaveEFI** » Mon Sep 26, 2011 6:26 pm

A bit of help. According to the bumf from Ramon, the SD1 type is actually hall effect producing a square wave, but two wires rather than three. So I'd try as I suggested, which turns it into a three wire type.

gelmonkey · Post by **gelmonkey** » Mon Sep 26, 2011 8:49 pm

Hi Again all
Well I have tried Autometers suggestion of running the earths from the sender and the guage to the block and fired the sucker up and guess what..
F**k all changed apart from the fact that when I turned the ignition on beforehand I used to see 16000 in the digital display now after trying the AM way I now get 550 showing in the display which says to me that now there really is a problem!
Never seen that figure before and AM say that you should always see 16000 when you turn the ignition on.
Have phoned Autometer now and am waiting for a call back,why not,use their phone bill instead of mine.
Will keep you posted .
ARRGGHHHH

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gelmonkey · Post by **gelmonkey** » Tue Sep 27, 2011 12:07 pm

Dave
Do you think that you could post a wiring diagram for me please.
I never got a call back from Autometer last night and to be honest I was really p@ssed that their advice did not make the slightest bit of difference.
As already mentioned I am not brilliant at wiring but think I should give it a go becasuse I dont want to send the speedo back to the USA unless I really have to.
To say I'm frustrated would be an understatement.

Cheers
P

russell_ram · Post by **russell_ram** » Tue Sep 27, 2011 1:45 pm

I agree with Dave here - the Rover sender is a two wire Hall effect. You need 12V supply and ground reference. I use on (admittedly with a smiths guage) and it works perfectly when wired correctly. The speedo is only counting pulses, so the fact you are using autometer shouldn't make any difference at all.

Russ

gelmonkey · Post by **gelmonkey** » Tue Sep 27, 2011 2:13 pm

Hi Russ
As you can probably tell all is not well in the Gelmonkey camp.
I have tried to energise the system and ground it but still nothing happened.
Just hope the speedo isnt a duff unit as I have already had to have a replacement fuel guage from them!

cheers
P

DaveEFI · Post by **DaveEFI** » Tue Sep 27, 2011 2:17 pm

This is what I'd try - adding a resistor.

It can't do any harm, and should add the ground to power the sensor electronics which is how I think the Rover speedo does it. But it really is a guess as I don't have a spare sensor to check out.

gelmonkey · Post by **gelmonkey** » Tue Sep 27, 2011 3:18 pm

Hi Dave
Thank you for the diagram.
Can I buy this kind of resistor at Maplins and should I just ask for a 1k resistor?
I will not be able to do anything with this now until early next week as I have to go and work in Trowbidge for the next couple of days on a Willy's Coupe and then Mrs G is away for the weekend so will be looking after the small people.
Thank you so much for all of your help and I will get this sorted just in time for the car to come off the road for the winter!!

Cheers
P

Ian Anderson · Post by **Ian Anderson** » Tue Sep 27, 2011 4:12 pm

gelmonkey wrote:Hi Dave
then Mrs G is away for the weekend so will be looking after the small people.
Cheers
P

Little people are good for electronic work
ask them to hold the nd of the wire and when it comes live they always let you know!

Like the time I was on a farm and said to my daughter that shock wire on the top of the fence is not working - she then had to touch it to check!

Ian

gelmonkey · Post by **gelmonkey** » Tue Sep 27, 2011 5:53 pm

Mr Anderson
you have a cruel sense of humour which I like.
However,my daughter does not like the pin up pictures I have in my garage and No2 son likes them too much so not the best place to have them help me.
As an aside some years ago George was "helping" me put the engine together for my car and I told him we were going to put the slugs in next.
He said "I'll go and get some for you dad"
"I have them here son " I said and then he vanished out to the garden in search of .....
Whilst they do have an enourmous amount of squish thems not quite the right ones.
Was only trying to help he was....
Kids!!

P