P0501 Vehicle Speed Sensor 1 Performance

[Ddays]

So Gruff decided to throw a P0501 code this yesterday and morning. Speed sensor Performance issue. This happens when it downshifts going up a hill. The brake warning light comes on and it will not shift up or down. This happened a couple different times. Mostly the brake light will go off a mile or so down the road and it returns to normal. Last time the light went off & stayed on. Turned it off & re-started & it went away. Dropped it off at the bottom of the hill for my buddys garage to look at. Ideas? Suppose it will hurt to drive it 4 hours?

 

[jeeeep]

So Gruff decided to throw a P0501 code this yesterday and morning. Speed sensor Performance issue. This happens when it downshifts going up a hill. The brake warning light comes on and it will not shift up or down. This happened a couple different times. Mostly the brake light will go off a mile or so down the road and it returns to normal. Last time the light went off & stayed on. Turned it off & re-started & it went away. Dropped it off at the bottom of the hill for my buddys garage to look at. Ideas? Suppose it will hurt to drive it 4 hours?

I wouldn't drive it, that can cause transmission damage. it's like driving the Jeep not calibrated properly for your tire size except in this case it doesn't go into limp mode

 

[Ddays]

If the tranny returns to shifting normally and it doesn't go into limp mode, how will that affect it?

 

[JKDream]

I wouldn't drive it, that can cause transmission damage. it's like driving the Jeep not calibrated properly for your tire size except in this case it doesn't go into limp mode

These are two completely different issues. A tire size outside of calibration MAY cause some extra wear if you drove it like that for a couple years.
The only real issue is the sluggishness from being in the wrong gear, similar to not having a regear.
** Edit: An ECU that isn't calibrated doesn't go into limp mode btw, it just shifts like shit.
An ECU that doesn't have the proper differential gearing calibrated does.

If the transmission is sticking to a gear, that isn't harming it, it just doesn't know when to shift because it's entirely computer operated and not reading the speed of the vehicle.

 

[jeeeep]

If the tranny returns to shifting normally and it doesn't go into limp mode, how will that affect it?

the way it was explained to me is the transmission is in a state of constant erratic shifting even though it seems normal when not under load because it's not sending and receiving the proper signal from the ECM.

the issue gets worse when under load - like uphill downshifting ...but it's basically doing that all the time just not as obvious.

may not do much damage in the short term but I'm a bit OCD on the prevention of possible costly repairs

 

[JKDream]

the way it was explained to me is the transmission is in a state of constant erratic shifting even though it seems normal when not under load because it's not sending and receiving the proper signal from the ECM.

the issue gets worse when under load - like uphill downshifting ...but it's basically doing that all the time just not as obvious.

may not do much damage in the short term but I'm a bit OCD on the prevention of possible costly repairs

You're still talking about tire size calibrations though. The problem is his transmission is NOT shifting.
It isn't hunting for gears, it's holding a gear.

 

[Ddays]

You're still talking about tire size calibrations though. The problem is his transmission is NOT shifting.
It isn't hunting for gears, it's holding a gear.

This ^^ exactly. Tire size is calibrated to the actual measurement I took of the tire, not the listed size. And I regularly rotate so unbalanced size shouldn't be an issue. The tranny will not even shift if I try to use the manual function - either up or down.
But when I stop, turn it off and immediatly restart it functions normally. This does not happen from a standing stop or during regular puttering around driving. It shifts just fine. This only occurs at speed (55-70) and only when the tranny downshifts.

 

[jeeeep]

i understand it's not shifting, i was just relaying how it was explained to me.

the sensor is not an expensive part and it's an easy fix - on mine it was the connector that was damaged- probably from catching something on the trail.

 

[Ddays]

i understand it's not shifting, i was just relaying how it was explained to me.

the sensor is not an expensive part and it's an easy fix - on mine it was the connector that was damaged- probably from catching something on the trail.

Gotcha. Its at the shop now so I'll see what they have to say. I just hope the hell I don't go into limp mode on the damn Pa turnpike, y'know?

 

[jdofmemi]

So I also have the P0501 code.
First I had the U140B and U140C, for left and right rear wheel speed sensor implausible input.

Before I got those fixed, while driving the brake warning light came on. Soon I came to a stop light, and something seemed off. When I pulled away, the Jeep was very sluggish, and I never felt a shift all the way to road speed. It seems the transmission did not downshift when I stopped. I hit several more stop lights and no downshift. I am pretty sure I was taking off from a stop in 5th gear.

When I could, I pulled over, shut off the Jeep, restarted, and pulled away. Uh oh! Now it is in 1st, and will not upshift. I tried clearing the codes with my JKS and no go. As soon as I hit 10 mph, the brake warning comes on again and no shift. I tried manual, no help.
The only thing that made it a little better is if I shut it off, restarted, and as soon as I put it in gear, go to manual and select 2nd.

It was a long 20 miles home in second gear

So I am replacing the wires to the rear speed sensors, but where is the one with the U0501 code found?

I'm having Jeep withdrawals, need to get it fixed

 

[Lama_Dad]

What did you do?

So I also have the P0501 code.
First I had the U140B and U140C, for left and right rear wheel speed sensor implausible input.

Before I got those fixed, while driving the brake warning light came on. Soon I came to a stop light, and something seemed off. When I pulled away, the Jeep was very sluggish, and I never felt a shift all the way to road speed. It seems the transmission did not downshift when I stopped. I hit several more stop lights and no downshift. I am pretty sure I was taking off from a stop in 5th gear.

When I could, I pulled over, shut off the Jeep, restarted, and pulled away. Uh oh! Now it is in 1st, and will not upshift. I tried clearing the codes with my JKS and no go. As soon as I hit 10 mph, the brake warning comes on again and no shift. I tried manual, no help.
The only thing that made it a little better is if I shut it off, restarted, and as soon as I put it in gear, go to manual and select 2nd.

It was a long 20 miles home in second gear

So I am replacing the wires to the rear speed sensors, but where is the one with the U0501 code found?

I'm having Jeep withdrawals, need to get it fixed

Did a google search and found this thread. What did you have to change to correct the issue you are having? Mine is doing the exact same thing. However I did find on my drive home if I put in neutral and kill the engine and start right back I can get to 4th gear which made the drive home a little quicker LOL.
Thanks

 

[jdofmemi]

Did a google search and found this thread. What did you have to change to correct the issue you are having? Mine is doing the exact same thing. However I did find on my drive home if I put in neutral and kill the engine and start right back I can get to 4th gear which made the drive home a little quicker LOL.
Thanks

When I replaced both rear wheel sensors, and the wiring and plug on the bad side, my problems were over.

Good luck