2002 TJ speedo not working

[srp0005]

Good afternoon from the UK!

Ive had this problem with my 2002 Jeep TJ for a while where the speedometer gauge doesn't work, while all the other gauges work fine. I gave the gauge cluster a test (the test where you turn the ignition 3 times while holding the trip button) and the speedo gauge moved about fine.
After looking online, i was led to believe that it was the speed sensor (on the transfer box) that was causing issues. After plugging in my obd2 reader, and driving about, i was getting an accurate speed reading from the readers screen.

From this i thought that it might be a connection issue, though there seems to be no visual probelems with the cluster connectors or wires. One thing thats preventing me from further inspection, is that i cannot find a pinout online for the 16 pin connector that i believe carries the speedo information.

Does anyone have an idea of the problem and/or have a pinout for this 16 pin connector?

many thanks, Sonny

 

[Obi-Wan]

There's a good chance your problem lies at the sensor on the transfer case or the wiring coming from the ECM to the cluster.

Here's the link to the 2002 FSM (Factory Service Manual). Speedo wiring starts at 8W - 40 - 3

Cluster C1 & C2 pin-outs are at 8W - 80 - 25

 

[srp0005]

There's a good chance your problem lies at the sensor on the transfer case or the wiring coming from the ECM to the cluster.

Here's the link to the 2002 FSM (Factory Service Manual)

I assume that the sensor on the transfer case works as i get an accurate speed reading when i use my obd2 reader while driving. From that then the wiring from the ecm to the cluster should be the problem. Im having trouble tracing where the cluster wires run to in order to test this. I also haven't been able to find the pinout from the service manual either. Many thanks for the link though.

 

[Obi-Wan]

Im having trouble tracing where the cluster wires run to in order to test this. I also haven't been able to find the pinout from the service manual either.

VSS wire B27 (white / orange) runs to EMC connector C2 (WHITE)

ECM C2 Pinout. Pin marked in red.

Cluster pinout

 

[srp0005]

Ive located the plug, now how can i test the signal from the ECM to the cluster? Sorry if this question seems a bit obvious ( im not great with vehicle electrics).

 

[Obi-Wan]

The VSS signal is going to be sent to the cluster via the PCI BUS along with a bunch of other data. There's no way without advanced diagnostics tools to sniff out the VSS signal from the rest (e.g. you cant just use a multimeter)

From the manual.....

The DaimlerChrysler Programmable Communication Interface (PCI) data bus system is a single wire multiplex system used for vehicle communications on many DaimlerChrysler Corporation vehicles. Multi-plexing is a system that enables the transmission of several messages over a single channel or circuit. AllDaimlerChrysler vehicles use this principle for communication between various microprocessor-based electronic control modules.

You would need to get your hands on a DBRIII scan tool or equivalent (HINT: they're $$$$$$$$$$$)

 

[TheBoogieman]

The VSS signal is going to be sent to the cluster via the PCI BUS along with a bunch of other data. There's no way without advanced diagnostics tools to sniff out the VSS signal from the rest (e.g. you cant just use a multimeter)

From the manual.....

The DaimlerChrysler Programmable Communication Interface (PCI) data bus system is a single wire multiplex system used for vehicle communications on many DaimlerChrysler Corporation vehicles. Multi-plexing is a system that enables the transmission of several messages over a single channel or circuit. AllDaimlerChrysler vehicles use this principle for communication between various microprocessor-based electronic control modules.

You would need to get your hands on a DBRIII scan tool or equivalent (HINT: they're $$$$$$$$$$$)

View attachment 617319

 

[srp0005]

There's no way without advanced diagnostics tools to sniff out the VSS signal from the rest

You would need to get your hands on a DBRIII scan tool or equivalent (HINT: they're $$$$$$$$$$$)

View attachment 617319

Oh....

I'm really not sure where to go from here. I guess theres got to be a way of finding the problem without having to get one of these scanners or replacing every component that could be causing an issue.

 

[macleanflood]

Try continuity and ohm tests...just make sure the wire runs correctly from the PCM to the cluster.

-Mac

 

[srp0005]

Which wire on the cluster side is for the speedo? i read somewhere that it is an orange wire though I feel like I'm just making things up

Try continuity and ohm tests...just make sure the wire runs correctly from the PCM to the cluster.

-Mac

That sounds like the way forward. I'll have a go tomorrow

 

[srp0005]

I have just tested the pci bus wire between the cluster connector C2 and c203 (the green dashboard one) and there is good continuity. Same between the obd2 port and c203. The wire between the white PCM connector pci pin and the cluster connector seems fine too.

Could there be a chance that the speed reading i was getting from the obd2 connector was from the wheel speed sensors rather than the speed sensor on the transfer case?

 

[macleanflood]

I don't think there are wheel speed sensors...but then I have a 97 with no ABS.

Pretty positive all TJ/LJs get their signal from the transfer case speedo gear.

If your PCM sees the right speed, and the wires are intact...then it's got to be the cluster...have you checked the cluster to look for any damage... sometimes you can see damage to the circuit board.

I'm guessing the self test shows the motor working the needle but not necessarily verifying communication with the PCM.

-Mac

 

[srp0005]

Nothing looks damaged in here though its hard to tell.

I haven't moved the jeep in a while so im gonna see if messing about with the connectors has sorted out the gauge issue.

 

[srp0005]

No luck. While i still get a speed reading from

 

[srp0005]

No luck. While i still get a speed reading from

Sent accidently mid sentence

While I'm a speed reading from my obd2 reader, there is still no output from my speedometer .

 

[macleanflood]

Thinking you need to send the cluster someplace for repair.

Let me know if you're not having luck searching the forums... unfortunately most of those repair places are across the pond.

-Mac

 

[srp0005]

Thinking you need to send the cluster someplace for repair.

Let me know if you're not having luck searching the forums... unfortunately most of those repair places are across the pond.

-Mac