Speedo moves while idle

GS608 · 19-09-2010, 04:23 PM

Just wondering if anybody has experienced this issue before. After coming back from a quick drive and putting the car in park i noticed that the speedo moved up and down while the car was idling, rev it and it shoots up with the revs, has done this before at traffic lights while in drive, just fluctuates slowly though not as dramatic as when i rev it in park. I took a little video as im hopeless at explaining things, hopefully somebody knows what the problem is, might be a ground issue? as when headlights are on and the indicator is turned on the climate control lighting flashes with the indicator, or dims when i press the brake etc.

Video HERE

321Go · 19-09-2010, 07:07 PM

Correct. It is a earthing issue. Check your earth cables. Run a short cable from the top alternator mounting bolt to neg on battery. A couple of extra earthing cables from chassis to engine, chassis to gearbox will also help.

GS608 · 19-09-2010, 08:17 PM

Thanks for the reply mate, rep coming your way

Mr Hardware · 19-09-2010, 11:14 PM

Y'know, i don't necessarily agree. I had this problem, i thought it was an earthing issue, i earthed everything that could be earthed. No change. Eventually found it was the speedo transducer at fault. The backlight of the odo and such dimming with the blinker is not a fault, i'm relatively thats just normal.

Mr_Monty · 19-09-2010, 11:46 PM

Quote:

Originally Posted by Mr Hardware

Y'know, i don't necessarily agree. I had this problem, i thought it was an earthing issue, i earthed everything that could be earthed. No change. Eventually found it was the speedo transducer at fault. The backlight of the odo and such dimming with the blinker is not a fault, i'm relatively thats just normal.

+ 1

I do believe this is known as the VSS, and u'll find right at the back of the gear box just before where the drive shaft goes into gear box. has a red line coiming from it, 3 wires.

Jimmyd · 20-09-2010, 09:03 AM

Quote:

Originally Posted by Mr Hardware

Y'know, i don't necessarily agree. I had this problem, i thought it was an earthing issue, i earthed everything that could be earthed. No change. Eventually found it was the speedo transducer at fault. The backlight of the odo and such dimming with the blinker is not a fault, i'm relatively thats just normal.

Quote:

Originally Posted by Mr_Monty

+ 1

I do believe this is known as the VSS, and u'll find right at the back of the gear box just before where the drive shaft goes into gear box. has a red line coiming from it, 3 wires.

Have to concur that in my experience this was the most common cause. Thats not to say earthing is not the issue of course....

Cheers

James

EF-MattyB · 20-09-2010, 09:12 AM

Hey mate,

My 99 AU Fairlane ghia does the exact same thing. Although mine is very intermittent. It will occur maybe once every week and it doesnt follow the revs. I will be pulled up at a set of lights and the speedo will shoot up to 40 down to 20 and just bounce up and down.

Once i drove off it seems to be fine.

KR1STO · 20-09-2010, 02:42 PM

I had the same with mine...
Changed the speedo transducer and the problem went away..

sd1800 · 20-09-2010, 03:14 PM

I also have the same problem with mine but it does it so rarely I just put up with it.

GS608 · 20-09-2010, 06:21 PM

cheers guys for the other opinions, i believe there is a earth issue as well anyway as the climate control backlighting dims with indicators also the alternator light has been on for about 2 months now after i replaced it with one from a wrecker (volt stays up at 13.8 but light has been on since then, no starting issues or anything).

Will have a look at the speedo transducer, are they an expensive item to replace?..like yours sd1800 it happens rarely but might as well fix the issue if it isnt too pricey.

JC · 20-09-2010, 08:41 PM

I had this in one of my AUs. Took it to the auto trans shop, and as soon as I said what's happening, they asked if I had any WD40? Of course I did, so they told me to unplug the plugs on the side of the gearbox and spray both the plug ends with WD40, shake them out then reconnect. Instant fix.

Mr Hardware · 20-09-2010, 10:19 PM

Yeah from memory transducers are only a two-figure cost item

JC · 21-09-2010, 12:09 AM

Quote:

Originally Posted by Mr Hardware

Yeah from memory transducers are only a two-figure cost item

so between $10 and $99. Not too bad I spose.

Jimmyd · 21-09-2010, 09:25 AM

feebay prices vary from $45-$90

JC · 21-09-2010, 09:29 AM

WD40 costs $5 a can, and should resolve the issue - it's caused by dirty contacts in the plug/s at the transmission.

Jimmyd · 21-09-2010, 09:35 AM

Quote:

Originally Posted by JC

WD40 costs $5 a can, and should resolve the issue - it's caused by dirty contacts in the plug/s at the transmission.

also a common cause for activating Limp Home Mode and erratic shifts

Mr Hardware · 21-09-2010, 10:35 AM

yeah talk about erratic shifts
it sucks when you're just taking off from the lights then the speedo decides to go to 140 and change into top
it had me manually shifting there for weeks

sly · 13-02-2011, 11:25 AM

Well, I thought I was the only one with this problem. My speedo has been intermittently moving in sync with the tacho at standstill for years. It started around the same time the car started going autistic with a J3 chip fitted, so I thought they were related. Now it's also happening in my wife's AU3 wagon.

So, 2 reasons to get under the car(s) with a can of WD40. 3 actually, because my gear position switch is also giving me grief. I have to start the car in 'N' almost all the time now, 'D' rarely works. The switch is fairly new, too, but everything down there is caked in oil, cowpat and dust. I reckon I need to spray out all the connections to the tranny.

SVT8 · 13-02-2011, 06:56 PM

i just came on the computer now to search for this problem!!!.

Mine's been doing exactly the same thing only at idle and noticed that the speedo takes it time to drop down to 0km when you come down to a stop in D. Also noticed when this is happening i couldnt change the speed selection with my wipers? then as soon as i took off in drive the wiper speed corrected itself?.....speedo transducer wont be related to that will it more likely a bad earthing?

Rustydumper78 · 12-07-2016, 10:29 PM

I Have a similar issue with my BA ute. Unstable speedo needle at speed and occasionally when stopped at lights and my speedo is out by 55km at 100km/h (100Km/H on GPS is 155Km/h on speedo). Changed transducer, drive gear, driven gear (Even tried different teeth combinations), no change. Cleaned earths checked battery no change. I ran a meter over the three wires that go to transducer (Wiring loom that goes to PCM) and found that two of the wires "short" back to each other, can anyone tell me if this is right? I have looked at the wiring diagram but struggle to tell if i am testing it right.

My method was to disconnect the PCM to avoid any interference, inspected the wires for physical damage but found none. can anyone help this is driving me crazy.

If its an earth issue how can i fix this?
Thanks

mntleb6 · 02-07-2017, 04:07 PM

Quote:

Originally Posted by Rustydumper78

I Have a similar issue with my BA ute. Unstable speedo needle at speed and occasionally when stopped at lights and my speedo is out by 55km at 100km/h (100Km/H on GPS is 155Km/h on speedo). Changed transducer, drive gear, driven gear (Even tried different teeth combinations), no change. Cleaned earths checked battery no change. I ran a meter over the three wires that go to transducer (Wiring loom that goes to PCM) and found that two of the wires "short" back to each other, can anyone tell me if this is right? I have looked at the wiring diagram but struggle to tell if i am testing it right.

My method was to disconnect the PCM to avoid any interference, inspected the wires for physical damage but found none. can anyone help this is driving me crazy.

If its an earth issue how can i fix this?
Thanks

I've just had my ba lpg ute fixed which has had this issue for the last 2 years.
Ever since plugs and coils had been replaced I've had this issue. Didn't happen all the time, which made it very hard to find the problem.
I spoke to the guys at ford and they told me to replace the plugs and coils, it was almost due for plugs again anyhow.
They have apparently had a few ba/bf that have had weird things go on after plugs and coils have been changed. More so noticeable in the straight lpg.

They told me to put genuine plugs and genuine coils in.
It originally had ngk plugs and vdo coils. The problem has been there ever since they were fitted 80,000ks ago.

I purchased a set of genuine plugs.
I was going to use genuine coils, but got bosch ones cheaper.

I had them fitted and have had no problems with the car since.
No more speedo jumping around, no more stalling due to speedo saying the car was doing 220kph in park. No more limp home mode due to the car trying to grab 4th gear in park when the speedo went to 120kph.

Strongly suggest if your having this problem that you replace your plugs and coils.
Apparently this issue used to happen a lot in the au series aswell.

Coil choice either genuine or bosch (unable to tell who makes genuine ones, but bosch have made them all in the past so I took a gamble)

As you can buy genuine plugs cheaper than ngk, I would be using these. But entirely up to you.