Malfunction code 24

[TomD]

A while back my mechanical vdo speedo quit, check engine light came on and the scan master shows a code 24. Finally got around to replacing it and speedo works again but the check engine light stil comes on and the scan master still shows code 24 and registers 00 on the mph screen. The new speedo is accurate when checked against a gps phone app...

From this article, do I need to pull the power to the ECM to reset the code or what am I missing?

Thanks!

 

[TomD]

Well pulling the power didn't work, code came back... Hrmmmmmm....


I have a two piece speedo cable..... Guess I'll look at the VSS...

 

[machinegun]

usually vss issue. Stock speedos have it on the rear of the speedo but I thought the the GNX style gauges used an inline VSS.

 

[TomD]

usually vss issue. Stock speedos have it on the rear of the speedo but I thought the the GNX style gauges used an inline VSS.

Ok that makes sense. I have a Gnx style dash by avc. Here is a pic of the sensor between the two cables. Behind my dash, the red wire is taped off, and the green and black are going to the sensor. Can I buy a new inline 2 wire VSS or what are my options? The one I have now was manufactured by Arthur Allen and appears to be dated '94. Not sure if these or a replacement are still available.

 

[TomD]

Ok looks like I need what's called a hall-effect speed sensor...

 

[TomD]

Testing the sensor, AC voltage increased as I spun the drill which is a good thing.... What else could I check???

 

[RmvBfrFlght]

With only two wires on the VSS it will be a reed switch type. A Hall Effect would have three wires. The red behind the dash being taped off and using the green & black makes sense.

A Jags That Runs 2PRS is a 2K PPM reed switch type of VSS. Good possibility that it will work.

Arthur Allen went out of business some years ago. Not sure if they ever came back.

Strange that both the speedometer and VSS went out at the same time...

RemoveBeforeFlight

 

[RmvBfrFlght]

Measure the resistance between the two leads on the VSS. Slowly turn the VSS shaft, see if the resistance goes to infinity then back to close to zero. It should do this twice for each revolution of the input shaft.

It may be a magnetic VSS, in which case the AC voltage will increase as the shaft speed increases.

RemoveBeforeFlight

 

[TomD]

Ok yea I think the sensor is broken on account of the giant crack here. And also the magnet in the center barely moves when I try to spin it.

 

[TomD]

With only two wires on the VSS it will be a reed switch type. A Hall Effect would have three wires. The red behind the dash being taped off and using the green & black makes sense.

A Jags That Runs 2PRS is a 2K PPM reed switch type of VSS. Good possibility that it will work.

Arthur Allen went out of business some years ago. Not sure if they ever came back.

Strange that both the speedometer and VSS went out at the same time...

RemoveBeforeFlight

Reed type copy that, thanks. There is a magnet in the center as well.

I'm wondering if the VSS broke first and I didn't notice until the vdo gauge quit. I don't drive this one all that much but you would think I would have noticed the check engine light on... Unless the old vdo gauge somehow caused the cable to spin irregularly when it broke.... who knows. Thanks for the help!

 

[5gear]

Digging up an oldie here.... but, did you ever find a replacement or a solution?