When I regeared my 2001 Ram 1500 4x4, I forgot to put the tone ring onto the rear carrier, so my speedometer has been dead. After the regearing, when I'd come up to a red light or push the clutch in, the rpm's go straight to zero and the truck dies. It will crank right back up and as long as I'm moving and in gear I'm good. It does have a check engine light in for the rear speed sensor. Does unplugging it (similar to my situation) put the truck into some kind of limp mode?

I noticed my odometer hasn't worked since the regearing also. What I was thinking is, did the engineers make the truck go into some kind of limp mode, so people wouldn't just unplug the sensor if they wanted to drive the truck, but not put any miles on it? Thanks

 

If it were an auto trans, I could see it. But, with a manual trans? I don't think so.... Likely you have something else going on.

 

Now if you where a auto manufacture and wanted to stop people from doing just that what would you do? I had a guy i used to work with try this on leased vehicles, He was not successful. You also need to understand what "limp mode" is. Limp mode is where the pcm will use a default reading so the engine will still run and not use a bad reading(off the usable scale) that will cause the engine to stall. Speed sensors don't have limp modes they work or don't. Does it stall when you take it out of gear but still moving? Can you keep it running if you put you foot on the gas? Only way to fix the speedo/odometer is the put the tone ring back in. It also is disabling the abs.

 

When I press in the clutch I can keep it running if I want to, it is just a pain. I've noticed something else. When I crank up the truck I hear a pretty loud hissing coming from the engine. I took the breather off and looked down into the throttle body. There's the two main throttle valves sitting side by side, but the loud hissing is coming from a third whole in the back. After a few minutes of idling ruff, it almost seems like the truck goes, ok I want to stop playing around now, and something will change, the hissing from the rear hole goes away, and the truck will sit there and idle perfectly. Don't know if this applies to my other situation, but just wanted to throw it out there.

Trying to put the tone ring on today

 

Rear hole is the IAC well. If you see black stuff in there, you need to clean it out.

 

If you forgot the tone ring how did you get a proper gear pattern? I forgot a tone ring on my 8.8 (ford) for my Jeep. Couldn't get the slop out enough for proper gear/tooth contact pattern. Is there enough room for carrier bearing adjuster to take that much slop out?

 

The ring gear sat down on the carrier fine. The tone ring has a channel that it sits in. My pattern and backlash were good when I set it up.

 

So I guess the rear speed sensor did have something to do with the IAC Valve acting up. After I installed the rear chunk with the tone ring, I drove it around the neighborhood and when I got back home used my scan tool to clear the code for rear axle speed sensor not functional. I turned off the truck and then cranked it back up. It was still doing the hissing sound from the IAC valve port on the throttle body. I then did this thing to reset the IAC valve position. I saw a youtube video were a guy said to lightly apply the gas pedal then start the truck for 5 seconds and then turn it off, wait 10 seconds, then restart. Worked like a champ. No more hissing and the truck sat there and idled perfectly. It also wouldn't cut off when I came up to a stop sign and pushed the clutch in. My guess is that code that was in for the rear speed sensor wouldn't let the IAC valve be recalibrated.

But, I unfortunately have bigger issues going on...

 

Their is an outside lip in the gear that the tone ring goes in, it doesn't affect your gear setup at all.