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Speedometer not working

Tiny
BOS1957
  • MEMBER
  • 2003 JEEP LIBERTY
  • 3.7L
  • V6
  • 4WD
  • AUTOMATIC
  • 168,000 MILES
Rear axle assembly failed, replaced it with one from the salvage yard. Now the speedometer does not work, replaced ASB sensor from old differential still nothing. I'm thinking maybe I pulled on the wire connector to hard. But I checked it with my multi-meter there is 12 volts on the yellow wire, but should I have any power on the green?
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Wednesday, July 1st, 2020 AT 6:46 AM

10 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
You are correct that this is the most likely issue because the ABS needs to calculate the wheel speed and then it sends it to the PCM which then sends it to the cluster.

If you have 12volts on the yellow wire, that is correct but you should have the signal back from the sensor. So if you have 0 volts on the other wire then that is the issue.

Due to this being a used axle, we need to ensure it is equipped the same as your vehicle. Do you know the part number off the axle or at least what year and model vehicle it came out of?

If you swapped the sensor from the other unit and it was working prior and it is still not working then we can assume the sensor is not the issue. That means, it may be mounted to far away from the tone wheel. Speaking of the tone wheel, we need to make sure there is a tone wheel in the rear end. You should be able to use a borescope to look down the sensor hole and see the tone wheel.

Let's start with this info and go from there. Thanks
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Wednesday, July 1st, 2020 AT 4:09 PM
Tiny
BOS1957
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  • 23 POSTS
Thanks. Let me see if can get a number off this rear, it's supposed to be the same year they went by the VIN.
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Thursday, July 2nd, 2020 AT 7:59 AM
Tiny
BOS1957
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  • 23 POSTS
I haven't found a number on the housing yet, but it did look identical to the old one and both had the sensor in the same location. And I get the p0500 code an the engine light is on but not the ABS light if this means anything. Thanks again i'm still looking for number.
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Thursday, July 2nd, 2020 AT 2:19 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. I attached the testing but that is just confirming that you are not getting a vehicle speed signal. Take a look at the testing.
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Thursday, July 2nd, 2020 AT 8:41 PM
Tiny
BOS1957
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  • 23 POSTS
Since the replacement rear end came with a ABS sensor I would take it that it has one. My question is, the yellow wire has 12 volts should the green wire have any reading at all when unplugged from the sensor?
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Thursday, July 9th, 2020 AT 9:46 AM
Tiny
BOS1957
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  • 23 POSTS
Tone wheel I forgot to mention.
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Thursday, July 9th, 2020 AT 9:48 AM
Tiny
KASEKENNY
  • MECHANIC
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The green wire is called the signal wire. This means the yellow wire supplies the 12 volts and then the sensor picks up the high spots of the tone wheel and when it does, it sends a voltage pulse back to the PCM. The speed/rate of this pulse tells the PCM how fast the vehicle is traveling. So it will not have any voltage when the connector is unplugged. When it is plugged in and the rear end is spinning it should have a high and low voltage signal that if you spin the rear slow enough you should be able to see on a meter if you back probe it.

The fact that you forgot to mention the tone wheel, was that the issue?
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Thursday, July 9th, 2020 AT 7:09 PM
Tiny
BOS1957
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  • 23 POSTS
No, when I originally asked my question I was told to use a boar scope to make sure it had a tone wheel, but I figured if it had the ABS sensor it would have the tone wheel. But since the sender wire should not be live unless it's getting a signal from the sensor I must have a wiring problem in the harness back to the gauge. So i'm going to check the wiring harness. Thanks I think this might be where the problem could be.
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Thursday, July 9th, 2020 AT 7:55 PM
Tiny
BOS1957
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The reason to check my wiring is that I did get a small amount of voltage from the signal wire with it unplugged from the sensor. That's why I think there's a short in that wire.
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Friday, July 10th, 2020 AT 8:56 AM
Tiny
KASEKENNY
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Oh. I understand. Yeah. Sounds like you are on it. Let me know what you find.
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Friday, July 10th, 2020 AT 8:35 PM

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