LS3 and VDO Singleviu 80mm Tachometer

[Paul.B]

Hi all. A long shot but has anyone installed this combination and managed to get the Rev Counter working?

I've installed a crate LS3 into a kit car along with the GM LS create engine control unit. I've also installed a VDO Singleviu rev counter. I've seen the needle flick a couple of times but basically it is not registering. I've tried changing the pulses setting but to no avail.

Any help/experience?


TIA

[stevieturbo]

Paul.B said:

Hi all. A long shot but has anyone installed this combination and managed to get the Rev Counter working?

I've installed a crate LS3 into a kit car along with the GM LS create engine control unit. I've also installed a VDO Singleviu rev counter. I've seen the needle flick a couple of times but basically it is not registering. I've tried changing the pulses setting but to no avail.

Any help/experience?


TIA

And what sort of signal is this rev counter expecting ? And what have you attached it to ?

[stevieturbo]

Assuming this is the instructions, it should be fairly straightforward either via CAN or via Pin5 to a coil trigger wire, or more suitably the tacho signal wire on the ecu ( assuming it offers this and the dash was not all CAN )

https://www.vdo.com/media/746713/en_user-manual-si...

[Paul.B]

Thanks for the replies

I'm attaching it to the tacho signal wire out of the ECU loom (Bulkhead connections) I've assumed this in an analogue signal and have the gauge set to analogue. The ECU instructions from GM state it is a 2-pulse signal.
I've tried a whole range of Pulse setting on the gauge set-up but still no reading.

As a side, the GM instructions mention some users may need to add a resistor to the circuit. I've ordered a range from 1k 1/4 watt to 5k ohm. Electronics are a complete mystery to me so I've no idea how this would help???

Edit: Yes, those are the instructions. I'm using the 8-pin multi-plug and only attached the 12-pin with a +ve feed via pin 12 for the initial set-up. No CAN being used.

Edited by Paul.B on Friday 4th October 18:20

Edited by Paul.B on Friday 4th October 18:21

[stevieturbo]

And does your ecu not have CAN ? it really should have.

Their wording is odd. It says analogue, and the voltage range it suggests for that input is 0-6v.

However any signal from anything half modern will be a simple square wave signal, which is more usually classed as a digital signal, not analogue. Although it is made up from an analogue voltage going up and down, albeit in what is considered a digital format.

Get a suitable scope or multimeter with frequency or rpm available and confirm you are even getting a signal from the ecu. Although there isn't any reason you shouldn't be if you're on the correct pin.

[GreenV8S]

stevieturbo said:

any signal from anything half modern will be a simple square wave signal, which is more usually classed as a digital signal, not analogue.

Perhaps they are using the term digital to refer to a binary encoded message, and analogue to refer to a simple regular pattern of pulses.

Getting analogue mode to work will probably require converting the ECU output signal to the signal characteristics that the gauge expects. When I've done this in the past it's involved using voltage dividers and pull/pulldown resistors, sometimes adding inductance to get a big enough signal swing. This would be tricky for somebody without electrical or electronic skills. It would seem far simpler to get the digital mode working since that should just involve finding compatible settings on both sides.

[stevieturbo]

GreenV8S said:

Perhaps they are using the term digital to refer to a binary encoded message, and analogue to refer to a simple regular pattern of pulses.

Getting analogue mode to work will probably require converting the ECU output signal to the signal characteristics that the gauge expects. When I've done this in the past it's involved using voltage dividers and pull/pulldown resistors, sometimes adding inductance to get a big enough signal swing. This would be tricky for somebody without electrical or electronic skills. It would seem far simpler to get the digital mode working since that should just involve finding compatible settings on both sides.

Possibly. Either way, them stating 0-6v, does suggest it wants a simple square wave signal.

Although the gauge does seem to be able to use CAN, in which case you could get more data than just rpm

[E-bmw]

stevieturbo said:

GreenV8S said:

Perhaps they are using the term digital to refer to a binary encoded message, and analogue to refer to a simple regular pattern of pulses.

Getting analogue mode to work will probably require converting the ECU output signal to the signal characteristics that the gauge expects. When I've done this in the past it's involved using voltage dividers and pull/pulldown resistors, sometimes adding inductance to get a big enough signal swing. This would be tricky for somebody without electrical or electronic skills. It would seem far simpler to get the digital mode working since that should just involve finding compatible settings on both sides.

Possibly. Either way, them stating 0-6v, does suggest it wants a simple square wave signal.

Not sating you are wrong, but coming from a controls background, to me that would mean 0v = 0rpm, 6v = 6000rpm (obviously, I have chosen 6000 randomly, could equally be 8000rpm ar anything in between)

[stevieturbo]

E-bmw said:

Not sating you are wrong, but coming from a controls background, to me that would mean 0v = 0rpm, 6v = 6000rpm (obviously, I have chosen 6000 randomly, could equally be 8000rpm ar anything in between)

That would make no sense from how any other tacho would work.

They all get a pulsed signal of some sort. Whether that's from the regular flyback from an inductive coil, or a square wave signal from an ecu.

I don't think I've ever seen one take a simple variable analogue voltage ( even if ultimately the swing needle may see such a voltage )

[E-bmw]

stevieturbo said:

E-bmw said:

Not sating you are wrong, but coming from a controls background, to me that would mean 0v = 0rpm, 6v = 6000rpm (obviously, I have chosen 6000 randomly, could equally be 8000rpm ar anything in between)

That would make no sense from how any other tacho would work.

They all get a pulsed signal of some sort. Whether that's from the regular flyback from an inductive coil, or a square wave signal from an ecu.

I don't think I've ever seen one take a simple variable analogue voltage ( even if ultimately the swing needle may see such a voltage )

I am not disagreeing you in the case of a tacho signal, just from a controls point of view, as I said, if I saw that quoted & would assume a variable voltage 0 - 6v.

[stevieturbo]

E-bmw said:

I am not disagreeing you in the case of a tacho signal, just from a controls point of view, as I said, if I saw that quoted & would assume a variable voltage 0 - 6v.

I read from it....do not connect to a 12v inductive coil setup. Which could be damaging to it, even if it doesn't specifically say it.

As said though, need to scope what the ecu is outputting, and find more info or test what the gauge wants.

Or just use CAN

[E-bmw]

stevieturbo said:

E-bmw said:

I am not disagreeing you in the case of a tacho signal, just from a controls point of view, as I said, if I saw that quoted & would assume a variable voltage 0 - 6v.

I read from it....do not connect to a 12v inductive coil setup. Which could be damaging to it, even if it doesn't specifically say it.

As said though, need to scope what the ecu is outputting, and find more info or test what the gauge wants.

Or just use CAN

Correct.

[Paul.B]

Thanks again for all the replies. I'm away until later in the week. I'll go through them again and maybe post up the GM installation guide. Although I'm pretty sure it is only a couple of lines.
P

[chippy348]

I can't help other to say this guy helped me out with a Tacho on my Escort Cosworth when i switched over to Emtrion management.

Forgot to add the link !

https://spiyda.com/tachometer-electronics.html

[Paul.B]

Thanks again everyone. I've just come back to this issue and after some research found adding a 5k ohm 1/4 watt resistor between signal and 12v+ feed has brought the taco to life.