theres two important key items i have yet to hear anyone talk about... the BCM and the PCM. if non ABS the wires are routed directly to the BCM. the BCM then sends signal to the PCM and instrument cluster. theres a manual guage sweep you can perform to ensure the cluster isnt the issue. key out of ignition hold the trip/reset button. put the key in and turn to acc position while holding trip/reset. all gauges should sweep on your dash if the speedo doesnt do this then replace the cluster. if this checks good theres a orange wire that communicates from PCM to BCM. test this wire for continuity. at the diff speed senor test the yellow wire for 12V. check the yel/blu wire for 5V reference. if no 12V/5V ref signal, the BCM is likely the cause the yel/blu wire should create a wave signal test this by installing a multimeter on the yel/blu wire and the other end of meter directly on the sensor - (right side terminal in the sensor). select the AC/Voltage on meter.as the wheels turn the it should generate AC current if not replace the sensor. many ppl say the PCM controls the speedo but this isnt so on a non abs jeep. if equipped with ABS then the PCM is likely the cause. hope this helps
Thanks for your reply buddy, my speedometer was acting up and suddnly stopped working and then started stall and then stopped starting, after changing speed sensors, problem did not go away, and I came across your post and I checked the rear differential sensor wires, nothing seemed broken, and I opened the wrapping and checked the wires inside, guess what I found, broken wire. I used a connector and connected the wire and it solved the problem, everything works fine, all error codes and check engine light is gone, I wanted to thank you. I sincerely appriciate your post, My mechanic first suggested to change the two sensors and then the computer itself, but I wanted to dig in on the interenet and I your post saved me lots of money. thanks again
Speedo doesn't work and jeep is stalling
My husband picked up speed sensor wiring harness and plug $60 the old wires and plug had disintegrated when he took them out, when he replaced them at first the wires were backwards and speedo still didn't work he reversed the wires and speedo works no more stalling and engine light went out!
'04 Jeep Liberty Speedometer Problem
Has anyone ever fixed the speedometer on a 2004 Jeep Liberty? Seems like this is a BIG problem with them. We have replaced 2 speed sensors (one on transmission and one on rear end), also changed the ignition switch. The wires that run from the rear of Jeep are still enclosed in the original tubing and no signs of rubbing on anything. My Jeep shuts off when I slow down. Anymore ideas of what to check? The Jeep is a 5 speed with a 3.7 engine and 4x4.
Originally Posted by MajorOutlaw View Post
Your information has been very helpful, thank you very much. I did the tests, the gauge sweep succeeds. 2002 Jeep Liberty Sport 3.7 speedometer and odometer not working, all other BCM functions seem to operate properly.
- Instrument cluster passes diagnostic testing, speedometer gauge sweeps as expected.
- Replaced the rear differential speed sensor
- Measure 14V on pin 1 (12 volt p/s) at the sensor.
- Performed continuity tests on both wires leading back to the BCM (non-ABS), both passed, pin out BCM Harness C2 - pins 20 p/s (pink orange) and 21 signal (dark green orange).
- Checked the grounding at BCM and PCM.
- Checked continuity between the the PCM / BCM PCI data bus - PCM harness C3 pin 30 yellow/violet and BCM harness C1 pin 15 yellow/violet. Did not find orange cable on BCM you referred to, or other wire description the would lead back to the PCM looking through the service manual. Orange on the PCM is 5 volt supply.
- Spliced into the sensor signal at the BCM harness - and observed mVAC when the tires rotate, increasing as the rotation increased with one lead to the sensor output and other to the sensor input, and p/s supply pin disconnected.
- Did a new temporary test cable run for the rear wheel speed sensor signal directly into the BCM.
- Did not measure 5VDC on yellow/blue wire at all. I measured 12Vdc across yellow/blue wire with the car running and the 12V supply connected. I got a little mvDC on the sensor input / ground and car on. So according to you, and other things I have read, I should replace the BCM?
From what I read, and your posted rear differential sensor terminates to the BCM on non-ABS systems. From the BCM it shares data with the PCM via PCI data bus. It is the PCM that then notifies the instrument cluster though PCI data to sweep the needles?
Sending the BCM out for repair is a big step. My gut keeps telling it's not the BCM because these things hardly fail, and the other functions work fine, but logic points to the BCM. I'm out of things I can think of checking without a Chrysler DRB III scantool.
Any other suggestions? Did I missing anything? Has any else ever had to replace the BCM to resolve a speedometer issue?
Last edited by jeepowner24; 04-15-2019 at 03:54 PM.
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