Speed Sensor Indexing

I need some assistance. I know that the numbers on the speed sensor corresponds to the number of teeth on the speedometer gear. I also know that this number needs to be indexed. My question is where do you index the number to? I wasn't paying enough attention when I removed the sensor and I am not sure it is now in the right place. What problems can happen if it is not in the right place? In my own defense, it was very dark under there.

I'm not sure I understand what you're asking. The # of teeth calibrate the speedo to the gearing, tire size, etc. There is no "index mark" like on a timing chain. You put it in any old way as long as the gears mesh and the housing seats fully.

From 99 FSM: Note index numbers on adapter body. These numbers will correspond to number of teeth on pinion. Rotate adapter until required range numbers are at 6 o'clock position. Be sure range index numbers correspond to number of teeth on pinion gear.

This picture should help with the explanation of Al S.

Saudade said:

I'm not sure I understand what you're asking. The # of teeth calibrate the speedo to the gearing, tire size, etc. There is no "index mark" like on a timing chain. You put it in any old way as long as the gears mesh and the housing seats fully.

Click to expand...

It's that "so long as the gears mesh" that indexing is for. Since the various gears are a different diameter, the shaft is off center in the adapter body. It is rotated to get the right mesh. Back in the days of speedometer cables you could do this by feel, but since you can't detect backlash in an electronic sender, you align it to index marks instead.

Ah... thanks Matt! So its not indexing the gear, it's indexing the housing to ensure proper engagement. The "off center" is pretty obvious in the drawing above (thanks CharlesS).