No Speedo Reading / Wont shift

[oracian69]

Hi guys, 02, CRD.

This Jeep has been sat for a while, and had various 700 codes and a couple battery voltage related. The shifter board was known to be bad so I have replaced the shifter board PCB with a new improved one - thanks jeepswj.

The transmission oil and filter has been changed, the codes were cleared, and its had a full service, new battery.

Took it for a test drive and it still wont shift up at all - max 25mph or so. Reverse is fine.

The speedo is not showing any speed at all - which I am guessing is why it doesnt know when to shift. Speedo does test out ok - holding the button down when turning the ignition on makes all the dials move ok.

Its now not showing any error codes and no engine check light.

Im a bit stumped without codes. What shall I check next? Any ideas?

Thank you!

[bodgie]

I'd have thought there'd be a code for sure, are you using WJJeep Diag pro to check for codes? If so have you checked codes across all of the modules?

[oracian69]

Im using WJDIAG Pro with a Viecar OBD adapter. Ive been through all the sections - engine, trans, abs etc. the only code showing is an AC Low Voltage code P0530.

Really odd this one. I was thinking perhaps the ABS / wheel speed sensors have gone bad, but surely they would show codes for "implausible speed" or similar.

[bodgie]

Originally Posted by oracian69

Really odd this one. I was thinking perhaps the ABS / wheel speed sensors have gone bad, but surely they would show codes for "implausible speed" or similar.

Very odd, I'd reckon there would be a code or two present too. Voltage as in low voltage can do weird things, how good is the battery? Seems odd to suggest but another battery may fix a lot of problems, certainly won't be the first time it's done the trick.

You can display live data in WJDiag Pro, perhaps it may be an idea to see if the TCU is seeing speed.

Jason

[Fishframe]

My first thought is torque converter.

[nudibranches]

Maybe unrelated but.....check the transfer case voltage on the wjdiagpro in live sensor readings. I had a problem with voltage all over the place and it did weird things with the tranny, and often there was no code.

If the voltage isn't in spec range (as below) then it stuffs things up with the ECU and tranny.

In my case, I suspected it was wires, but in the end if was actually the plate within the transfer case that was worn and the switch was moving in and out.

As mentioned, might not be related but very easy to check.

4 Low 0,16....0,40 volts
Neutral 0,68.....0,97 volts
4 Hi 1,24....1,55 volts

You want voltages more or less in between the two readings, and constant.

[oracian69]

Thanks Nudibranches - I will check that..

An update however.....

I have used WJDIAG PRO and I have saved a load of the sensor data in excel format.

I have compared all my values with ones on the WJDIAG website, and my values all seem to be within the range of averages they publish for engine and transmission, EXCEPT I am not getting ANY speed data values from any wheel LF / RF / LR / RR Wheel Speed rpm values are all 0.

There are no stored codes, no engine light. Battery is A1, new condition, all voltage values seem good.

Surely not all 4 wheel speed sensors could be bad.....? And if they were surely it would log "implausible speed" or similar?

Maybe its a bad TCM?