Anyone had this problem ?

kiwijims · Guru

Anyone had this problem ?

03_Troopy · Guru

K.J try doing a Google on the fault you have and you will see there are a few things that could cause a fault similar to yours, from unserviceable speed sensor (damaged gears) to bad solder joints on the PCB on the instrument cluster.

Jaahn · Guru

Hi kiwjims, smile

Probably caused by a bad connection somewhere. As it happens in the driveway, probably not stripped gears smile . Try checking the connections underneath and spraying them and removing and replacing them a couple of times. Also the dash connections if possible. A dry joint on the circuit board is possible too but you will need some pointers off Google to go there probably

good luck Jaahn

kiwijims · Guru

Hi Guys. Thanks for the advice, I've tried a Google search on this problem but there isn't a straight answer there !!

I have found out that there is no speedo cable as it is driven electrically off the rear of the alternator,

There is some suggestion that there may be a small electric motor of sorts on the rear of the speedometer and this could be failing.

I had hoped that there is some "Grey Nomad" on this forum who has had the problem and can say,

"yep" what you have to replace is this and that, there is still some hope that someone has an old banger like mine ( 89 Model )

She done us proud by towing our old Classic caravan right around the Country, incl Tassie, with-out any major problem.

RoadsidebreakbetweenCoolgardieNorse[1].jpg

dorian · Guru

Here is a thread where someone narrowed down a similar fault to dry solder joints around a 4MHz crystal:

www.patrol4x4.com/forum/nissan-patrol-gq-y60-ford-maverick-11/speedo-problem-121490/

03_Troopy · Guru

Easy enough to go over the board with a jewellers loupe and inspect the joints. That used to be the way I had to find probably 50% of faults in TV's when i was in the game. Things like applying warm air from a hot air gun, or cool air from a compressor, while power is applied, can help to find bad joint too.

kiwijims · Guru

03_Troopy wrote:
Easy enough to go over the board with a jewellers loupe and inspect the joints. That used to be the way I had to find probably 50% of faults in TV's when i was in the game. Things like applying warm air from a hot air gun, or cool air from a compressor, while power is applied, can help to find bad joint too.

Now, to a bloke who knows what he is talking about,

What the heck is a jewellers Loupe, 03-Troopy? I picture something to hang rings on!! hmm hmm hmm

Pity you're not still in the game, You could receive a complete Dash Board in the Mail. biggrin biggrin

K.J. disbelief

03_Troopy · Guru

haha it one of those little eye glass thingies that jewellers and crooks use to inspect jewellery.

kiwijims · Guru

"OH I see" well I don't have a thingie in my boxes of caravan bits and pieces so.

I might haul the whole dash cluster out and throw it at an Auto Leckie to fiddle with. smile smile smile

Thanks for your thoughts anyway. Have one on me. biggrin

K.J.

03_Troopy · Guru

Hmm better to use an electronics technician, not many of your average every day auto sparkies have the tools or deftness of touch for PCB repair....

PeterD · Guru

kiwijims wrote:
I have found out that there is no speedo cable as it is driven electrically off the rear of the alternator,
There is some suggestion that there may be a small electric motor of sorts on the rear of the speedometer and this could be failing.

Are we talking about the speedo or the tacho? Tachometers use the AC frequency from alternators in diesels (petrol motors often use the ignition pulses.)

There will be a pulse generator somewhere down at the rear end of the gearbox that supplies the timing pulses for the speedo. You will have a problem somewhere from that timing generator through to the speedo and you are possibly picking up electrical interference that is exciting the speedo. Happy hunting, Apart from looking for dodgy wiring or plugs you will have to go to a higher authority.

Mike196 · Senior Member

G'day KJ,

Before you pull the dash out of the car have a real good look at the earthing for the instruments. Sounds like a bad earth to me.

Regards,

Mike.

DeBe · Guru

Had the same problem with a Maverick tacho when I was working for a Ford dealership. It finished up being a faulty IC which drives the meter. The IC was not available any where. Cheapest solution to the problem was buy a second hand unit from the wreckers.

03_Troopy · Guru

Mike196 wrote:
G'day KJ,
Before you pull the dash out of the car have a real good look at the earthing for the instruments. Sounds like a bad earth to me.
Regards,
Mike.

Which is most likely from a wire in a harness that connects to a connector on the PCB

kiwijims · Guru

Thanks again for all the good tips Guys,

I won't be doing too much today though, It's going to be 40+ deg here in Perth today !! wink wink wink

K.J. hmm

Aus-Kiwi · Guru

Often an earth issue.. Between motor and chassis...
Either add new cables?
Or clean existing where it attaches to block or chassis..
Some graphite grease helps conductability

Cupie · Guru

I have a similar long time issue with my 1995 Patrol Tacko.

Rises to around 1000. Stays there for a bit, then gradually rises as I go along until its on max. Gives me a hell of a fright when it suddenly chooses to work OK for a few minutes.

Found a local instrument specialist who said he could fix it but I never bothered (< $200).

I can judge the appx engine speed by ear ,,, at least good enough for my purposes.

ps. My reliable, old school, Auto Elec diagnosed it as the head, told me how to take it out & gave me the name of the instrument specialist.

-- Edited by Cupie on Sunday 21st of December 2014 06:40:17 PM

DeBe · Guru

Cupie, the problem with the tacho is the chip that drives it. Its not available, a lot of instrument panels have proprietory made chips made only for the instrument manufacturer.

kiwijims · Guru

Cupie wrote:
I have a similar long time issue with my 1995 Patrol Tacko.
Rises to around 1000. Stays there for a bit, then gradually rises as I go along until its on max. Gives me a hell of a fright when it suddenly chooses to work OK for a few minutes.
Found a local instrument specialist who said he could fix it but I never bothered (< $200).
I can judge the appx engine speed by ear ,,, at least good enough for my purposes.

ps. My reliable, old school, Auto Elec diagnosed it as the head, told me how to take it out & gave me the name of the instrument specialist.

-- Edited by Cupie on Sunday 21st of December 2014 06:40:17 PM

I'm inclined to think along your lines Cupie, I've been driving trucks to long to worry about the rev counter, going by ear is more reliable by far, I know what you mean about taking anything to a specialist, the first thing they mention is cost, and if it doesn't start in the hundreds, it will be by the time the item is returned to you.

I've already had this speedo from my patrol in to the shop once before when the trip meter played up, took a month to get it back, the part had to come from America and that cost hundreds. I think it's far cheaper just to ignore the needle flickering and judge you speed by eye sight ( watching for the sign on the side of the road saying speed trap ahead, placed by a good neighbour ) biggrin biggrin

K.J.

ST391GQ · Senior Member

I copped a similar problem with my previous Datto (92 ST30) after a flooded creek crossing. Got underneath and undid the plug that chases the wires to the electric speedo transponder on the rear of transfer....and gooey mud fell out. Now the creek wasn't muddy ....but years of gravel roads (Dust)....and creek combined to cause some craziness. A good spray with some WD40 to clean it and was fixed no worries..plus a seal up with some Lanetec some days later.

Not saying this is the answer to your problem....but start with simple first...ie...wiring ...plugs .....earths etc before going the mind boggling and expensive way.

HTH.

Cheers Keith

mr glassies · Guru

bad earth
dibs