AU Speedometer Trouble

DALLAS01 · 27-12-2009, 01:00 PM

Having trouble with the speedometer needle in my Series 2 AU Falcon. I replaced the sender unit located on the rear housing on the transmission. The problem seemed to rectify itself. 24 hours later the same problem came back. Not only does the needle jump around but the car power surges when the needle jumps.I disconnected the plug from the sender to the wiiring loom took the car out for a drive and although there is no speed reading the car ran smoothly. Does anyone have a solution or idea on what maybe the problem.

All help appreciated.

mik · 27-12-2009, 03:08 PM

thats very weird, sorry i`m no help at all, prior to all this why did you change the speedo sender?

disco frank · 27-12-2009, 06:10 PM

change the DRIVE gear in the extension housing

this is the gear that drives the spedo sender unit

the car will have issues as being an auto the ecu gets the speed info from the sender unit

if the drive gear is stripped out, the driven gear ( the one on the sender unit ) wont grip and turn correctly ! given false and oftern incorrect readings

Beer Baron · 27-12-2009, 06:43 PM

I'm with disco frank. Drop the tail shaft and unbolt the extension housing, Easy enough to do if you have stands. While you have the tail shaft and extension housing out you might as well replace the extension housing seal and bush.

I think automatic Au falcons change gears at certain speeds not rpm so if its getting the wrong speed signal it will play up changing gears and of course the needle will jump around.

Beer Baron.

disco frank · 28-12-2009, 01:06 AM

Quote:

Originally Posted by Beer Baron

I'm with disco frank. Drop the tail shaft and unbolt the extension housing, Easy enough to do if you have stands. While you have the tail shaft and extension housing out you might as well replace the extension housing seal and bush.

I think automatic Au falcons change gears at certain speeds not rpm so if its getting the wrong speed signal it will play up changing gears and of course the needle will jump around.

Beer Baron.

cheers

theu au uses the speed and rpm range alogn with the tps to determine gear selection hence why the adaptive shift on the ticcys works so good

when the speed sensor goes it goes straight into limp home mode!

the only reason i know this it damn happened to me and i was like WTF!
after changing the sender unit i was left with the drive gear as the only possible issue
it was up bad
and only had 150kms on it iff that too!

Mr Hardware · 28-12-2009, 11:38 PM

Transducer.

Quote:

I think automatic Au falcons change gears at certain speeds not rpm so if its getting the wrong speed signal it will play up changing gears and of course the needle will jump around.

correct.

4d47 · 26-07-2011, 09:12 PM

I had the same problem with a dodgy speedo and i cleand all the earth wires to the engine and body of the car and it seemed to fix it also improve the gear shift.nobody will believe this cause i couldn't

Rustydumper78 · 04-07-2016, 09:31 PM

I am having a similar problem with an 03 BA UTE, Speedo is out by 30+ KM/h (Ground Speed 100 Speedo 130). The needle will not stay steady and continually bounces so i can't use cruise control. I have changed Transducer, driven gear and drive gear in the gear box and i don't seem to be able to fix the problem. The original set up is 3.23 diff 8 tooth drive 19 tooth driven. I even tried 22 tooth driven and on had small reduction on speedo but still bouncing. Please Help