VDO Speedo / electrical challenge... Need electrical advice.

[yullose]

1kwikV6 dropped-off his GN today for me to take a look at some dash issues.

The pics are how it looks right now, the way it came to me...

Looking at the VDO instructions, compared to the Caspers instructions, I see different connections...
It's currently wired per the VDO instructions...

Who's instructions are correct ?

Without knowing for sure, I'm inclined to rewire it per the Casper instructions.

Currently the speedo works, but there's no speedo signal to the ECM.

The car came here with the conversion module "partially" wired, but not complete... so that may also be part of the problem. (no 12v+ connection)

I also have TWO tach modules here... one for the cruise(not yet installed) and one for the tach(already wired)...
I assume (according to the Caspers directions) the 2nd tach module is required to work the cruise circuit ???

Coupla pics here:

 

[RI-Matt]

I would think that if the gauge is working then the problem is elsewhere. The ECM should be getting it's signal from the hall effect sender and/or conversion module not the actual electric speedo.

Is that a Performance Industries dash?

Where is the speedo getting it's signal ?

When I did my GNX dash ( mechanical speedo ) the hall effect sender that was connected inline to the speedo cable had wires that were run to the stock optic head for the ECM to get it's signal.

My guess is you need to get that conversion module hooked up correctly and go from there. I wouldn't change the wiring of the speedo if it works now.

HTH

Matt

 

[yullose]

I would think that if the gauge is working then the problem is elsewhere. The ECM should be getting it's signal from the hall effect sender and/or conversion module not the actual electric speedo.

Is that a Performance Industries dash?

Where is the speedo getting it's signal ?

When I did my GNX dash ( mechanical speedo ) the hall effect sender that was connected inline to the speedo cable had wires that were run to the stock optic head for the ECM to get it's signal.

My guess is you need to get that conversion module hooked up correctly and go from there. I wouldn't change the wiring of the speedo if it works now.

HTH

Matt

The problem is... the Caspers conversion module instructions say to hook up the speedo differently than the VDO instructions.

I have no idea who's cluster it is... the car belongs to a friend. The speedo cable is connected to a sender... and three wires from the sender get hooked up. No mechanical cable connection to the speedo head.

I think I'm going to wire it exactly per Caspers schematic and see what happens.

This is the sender I'm working with...

 

[RI-Matt]

I think you're missing what I'm saying.
It doesnt matter whether the speedo gauge is wired the way Caspers says or not, the VSS converter should be getting it's signal from the same original source ( that big sender in your last post ) The speedo and ecm are not using each other for the signal. So as long as the VSS converter is wired correctly from the sender, then the ECM should read speed.
If the you change the wiring then the speedo gauge may not work.


Also, in the first set of pics, what are the two disconnected wires for ( a red one and a black one with a connector on end )

That sender is the same one as I used in my dash and no VSS convertor was needed, you just needed to hook two of the wires to the optic head wiring that goes to the factor VSS buffer. The white and black wires from the sender are attached to the green and black wires of the factory optic head wiring ( should be the green, red, black wires clustered together in last pic )


Matt

 

[yullose]

I think your missing what I'm saying. It doesnt matter whether the speedo gauge is wired the way Caspers says or not, the VSS converter should be getting it's signal from the same original source ( that big sender in your last post ) The speedo and ecm are not using each other for the signal. So as long as the VSS converter is wired correctly from the sender, than the ECM should read speed.
If the you change the wiring then the speedo gauge may not work.


Also, in the first set of pics, what are the two disconnected wires for ( a red one and a black one with a connector on end )


Matt

I understand now what you are saying.
Maybe I'll try leaving the VSS sender wired "as-is" so the speedo funtion isn't interrupted... and just piggyback the signal converter and tach module so the ECM and cruise module can see a 2-pulse signal.

The red wire was cut like that before the car arrived and is the 12V+ feed to the VSS converter module. The black wire is just a ground I pulled off to relocate.

 

[RI-Matt]

Art,
I added some additional info to my last post at the exact time you were replying to my post, so you might want to read the last part of my post as you might not need the VSS converter.

Also, was that sender attached to the speedo cable from the transmission?

Ask you buddy who made the dash, if it was from Tom Houser I think it can be wired to the factory VSS. I can email you the directions for that dash and the ones from AVC which made these kind of dashes also. Both dashes didn't require an additional VSS converter.


mptp98@cox.net


Matt

 

[yullose]

Art,
I added some additional info to my last post at the exact time you were replying to my post, so you might want to read the last part of my post as you might not need the VSS converter.

Also, was that sender attached to the speedo cable from the transmission?

Ask you buddy who made the dash, if it was from Tom Houser I think it can be wired to the factory VSS. I can email you the directions for that dash and the ones from AVC which made these kind of dashes also. Both dashes didn't require an additional VSS converter.


mptp98@cox.net


Matt

I'll forward the car owner a link to this thread...

Yes, the sender gets attached to the speedo cable. I only had it off to lube the upper cable since the owner said the needle was jumpy.

If I can wire this in a way to eliminate the aftermarket signal converter and add'l tach module, that would be great. The black/green/red VSS ribbon wire is still there and I assume is still attached to the OEM buffer.

The only issue I was concerned about is the pulse frequency output of the VSS sender. I *think* this is a VDO sender and outputs @ 16 pulses. The Casper unit converts the signal to a 2-pulse output for the factory ECM... and the add'l tach module enables the cruise module to also read the signal.

Maybe I need to do a little more homework before I start running wires.

If you want to send me any add'l info, that would be fantastic.

My email:

yullose001@yahoo.com

THANKS !

 

[yullose]

After talking to Dave (cars owner) I understand this is a one-of-a-kind dash cluster and was made from scratch by a friend.

It's pretty dang impressive looking for being a homemade unit.

I got most of the wiring done this afternoon, but now have a dim "voltage" light and non-functioning Scanmaster.

I think when I re-routed the ground wire to the VSS sender, I may have inadvertantly removed the source of ground to the rest of the cluster. I will investigate it next time in the garage.

 

[RI-Matt]

Art,
Just sent you an email with those directions.

That speedo sender looks exactly like the one used in my dash. I don't know if it's a VDO part or what, but I would try the wiring thing and see if it works.

Nothing to lose except for a VSS converter and additional tach module



Matt

 

[yullose]

I appreciate the info.

Both those sets of instructions are for a pass-through VSS sender and mechanical speedo.

The VSS I have now is a dead-head VDO/16-pulse unit... so there's no way it will function with the factory wiring or ECM, which requires 2 pulses. The speedo is also fully electonic and has no cable attachment.

I have to look at it tomoorow again.

I'm sure by disturbing the previous configuration, I have a few "new" issues to deal with now.

Here's a few pics...