[RRToadHall]

I have been having digital speedometor failures on an intermitant basis for a few days. Occasionally the car will die coming up to stop signs/lights. In my reading I am faily confident this is a VSS failing. I have new one in hand but sure can not locate the bugger. Everything I read says it is on the output shaft of the trasmission and to simply follow the speedo cable to it. According to the shop manual that is the speedo pinion NOT the speed sensor. Is this sensor part of the cruise servo? Elsewhere?

 

[Bob Lincoln]

Look for a diamond-shaped black plastic body bolted to the transaxle. If you follow the speedometer cable from the cruise servo toward the axle, it's at the end. Unscrew the cable, unbolt the sensor with a 10mm socket and pull straight up.

 

[geraldg]

OK what is the VSS ?

 

[Bob Lincoln]

Vehicle Speed Sensor.

 

[RRToadHall]

If I follow the speedo cable from the cruise servo to the transmission it goes into a white round, single bolt retention unit which is the speedometor pinion and looks nothing like the black diamond I received as a replacement. There are also no wires at that end of the cable.

The only thing I have remotely found in the shop manuals is a notation in the wiring schmatics that the speed sensor is located in the speeedometor cable, left fender side shield. Danged if I can find any shield on the left side.

 

[RRToadHall]

It jsut dawned on me that I have commited forum suicide by not including all my car specifics. This is a 2.2 turbo MFI. Cruise with digital dash.

 

[Bob Lincoln]

If I follow the speedo cable from the cruise servo to the transmission it goes into a white round, single bolt retention unit which is the speedometor pinion and looks nothing like the black diamond I received as a replacement. There are also no wires at that end of the cable.

That's it. It's a Hall effect sensor with a helical gear around the shaft. Undo the cable and bolt, and pull straight up (it's a very tight fit). Sometimes they could crumble, after all this time and heat exposure. The gear is not included in the replacement part, and so you transfer it from the old sensor.

Automatic or manual?

 

[RRToadHall]

If that really is the beast how come there are no wires on the old one? THAT is why I am banging my head. The old white round one has no wires or plug on it. I can accept change round for diamond shape and praying that with no sealing ORing that it won;t leak... but there are no bloody wires down there. :frusty:

Whoops... New Yorker, so it is an auto.

 

[Bob Lincoln]

I'll have to take a look at my car, should be the same. I know my analog speedometer is purely mechanical. Maybe the A/D conversion is done within the digital dash.

 

[RRToadHall]

I am open to any and all ideas at this point.

 

[RRToadHall]

Dawned on me that the conversion can't be done at the dash as there is no cable to the dash.

 

[Bob Lincoln]

Interesting. On the analog version with cruise, there is one cable from transaxle to cruise servo, and one from cruise servo to dash. I doubt that there is an A/D converter built into the servo, so if there are no wires at the speed sensor, and no cable to the dash, how does the dash acquire the digital input? Will check my 1984 service manual.

 

[RRToadHall]

Page 8-733, chart 18, top left. That is the only reference I have seen thus far.

y next step will be a full wire trace with crossed fingers and a glass of scotch... not necessarily in that order.

 

[RRToadHall]

auto section, page 21-60 shows the speedo pinion gear setup I have at the tranny end of the speedo cable.

 

[Bob Lincoln]

Says it's inline in the speedometer cable, but the diagrams for the cable don't show it there. Will have to look at my car tomorrow.

And it shows a speedometer cable to the dash in all cases.

 

[RRToadHall]

Yup on both accounts from what I have read... but I have no cable from the servo to the dash. Now ya have a better understanding for why I am so baffled.

Than again this is the car that had TWO timing marks on the intermediate shaft and monster fuel injectors that didn't even come close to matching what any manual said should be in it.

 

[RRToadHall]

Well it appears I have stumped everyone including Bob!

 

[mydodgedip]

Can you snap pictures of the replacement part and where both ends of the cable attach (Trans and cruise unit)? Might help clear things up or be good reference for others in the future.

 

[Bob Lincoln]

Maybe someone with a digital dash can chime in. I'm wondering if this was a homemade custom conversion, originally analog.

 

[B10alia]

Is it possible you were given the wrong part? The attatchment point for the cruise servo cable is a black diamond on my '95 Spirit. That has a purely digital setup (analog gauges driven by digital signal). There is no physical connection between the VSS and the cruise control via cable. The cable at the servo is the cable that operates the throttle linkage. At the throttle linkage, there are two more cables, one which goes to the kickdown linkage and the other to the accelerator pedal, for a grand total of three cables attatched to the throttle arm. I know we're talking a 10 year difference here, but if someone's been messing with the car, anything could really be in there. Hope this helps.