Daemon4x4 - 4x4 & Off Road Technical Board

Daemon4x4 - 4x4 & Off Road Technical Board

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#116-11-2011 12:42:06

Can I ask a question please.....(Speedo woes)

Can i ask a question please cus over there are ignoring me or don't know the answer.....

Speedo packed up last night and OD light flashes.

Found sensor check by mr bushwhacker :

Look at the plug end of the sensor and you'll see tiny numbers, 3 2 1.
Apply 12v to pin 1.
Earth pin 2. plus the negative probe of multimeter.
Positive probe of multimeter to pin 3.
Set meter to 20v DC, switch on power supply and turn the plastic cog on the sensor.
The voltage reading should fluctuate between 0 and 9 volts, if it doesn't then the sensor is stuffed.


After reading so many confusing threads i have concluded that:

If the speedo itself was duff the OD light would not flash as the signal to the ECU would still be there, the speedo is just incapable of displaying the result.

If the OD light flashes and the speedo does not work, its the sensor not sending info to the ECU which in turn senses a fault and triggers the flashing OD light, obviously the speedo does bugger all as the sensor is fubar.

So my question..... if i undo the bolt securing the sensor and pull it out will half a gallon of gearbox oil deposit itself on the nice company underground garage floor,
or do i wait till i'm at home and bung a bucket under it ????

#216-11-2011 13:41:55

Re: Can I ask a question please.....(Speedo woes)

Icon - Post link Paul1566 wrote:

Can i ask a question please cus over there are ignoring me or don't know the answer.....

Speedo packed up last night and OD light flashes.

Found sensor check by mr bushwhacker :

Look at the plug end of the sensor and you'll see tiny numbers, 3 2 1.
Apply 12v to pin 1.
Earth pin 2. plus the negative probe of multimeter.
Positive probe of multimeter to pin 3.
Set meter to 20v DC, switch on power supply and turn the plastic cog on the sensor.
The voltage reading should fluctuate between 0 and 9 volts, if it doesn't then the sensor is stuffed.


After reading so many confusing threads i have concluded that:

If the speedo itself was duff the OD light would not flash as the signal to the ECU would still be there, the speedo is just incapable of displaying the result.

If the OD light flashes and the speedo does not work, its the sensor not sending info to the ECU which in turn senses a fault and triggers the flashing OD light, obviously the speedo does bugger all as the sensor is fubar.

So my question..... if i undo the bolt securing the sensor and pull it out will half a gallon of gearbox oil deposit itself on the nice company underground garage floor,
or do i wait till i'm at home and bung a bucket under it ????
Only a dribble comes out when you pull the sensor from the hole.  Just don't drive the truck with it out or you'll leave a trail of gear oil down the road.

#316-11-2011 13:43:03

Re: Can I ask a question please.....(Speedo woes)

Cheers for that, will pull it out and test on the bench tonight....

#416-11-2011 15:18:44

Re: Can I ask a question please.....(Speedo woes)

Is the odometer still functioning?

#516-11-2011 15:23:30

Re: Can I ask a question please.....(Speedo woes)

No, the odometer and the speedo both stopped and the OD light started flashing....

#616-11-2011 16:12:39

Re: Can I ask a question please.....(Speedo woes)

Deffo sensor related then, by the sounds of it. Was just checking as a few seem to have been suffering from dry joints on the gauge cluster of late.

#716-11-2011 16:19:03

Re: Can I ask a question please.....(Speedo woes)

Dry joints on me gauge cluster sounds painful...............

Cheers

#816-11-2011 17:02:42

Re: Can I ask a question please.....(Speedo woes)

Icon - Post link Paul1566 wrote:

Dry joints on me gauge cluster sounds painful...............

Cheers
Only a dribble comes out when you pull the sensor from the hole.



Don't worry it's an age thing...you produce less as you get older... whistle

#916-11-2011 19:11:16

Re: Can I ask a question please.....(Speedo woes)

removed sensor and could not see numbers so switched ignition on and probed connector on truck to determine which pin was the 12v supply.
Went back to bench and connected sensor as bushwackers test and span the gear with rubber wheel in cordless drill.
got a constatnt 6.4 volts what ever speed the wheel span at.
Should the output vairy with speed ? or is it a pulse thing ?
It has got mph converter as the speedo has the k blacked out and seems to run nearly right as the policeman told me last week when i was slightly speeding home at 1am, he let me off with a warning. He told me roughly what i was doing and thats what my speedo said just before the blue lights came on in the rear view mirror.....
If the converter was fubar surely the ecu would not sense a fault as the fault would be on the input to the speedo not the input to the ecu ????
Don't want to take dash out to bypass converter if i don't have to. wouldn't know what it looks like anyway......

#1016-11-2011 19:26:39

Re: Can I ask a question please.....(Speedo woes)

It will be a pulsed output. To use a pure voltage based circuit would be insane.

#1116-11-2011 19:27:28

Re: Can I ask a question please.....(Speedo woes)

Don't spin it with a cordless drill as you won't see any fluctuation in voltage! roll

Just turn the cog by hand, it'll only take a 3/4 turn to register something, if it doesn't then it's gubbed.

#1216-11-2011 19:28:39

Re: Can I ask a question please.....(Speedo woes)

Icon - Post link Bushwhacker wrote:

Don't spin it with a cordless drill as you won't see any fluctuation in voltage! roll
lol I'd overlooked that bit. big_smile

#1316-11-2011 19:34:09

Re: Can I ask a question please.....(Speedo woes)

Toyota VSS types here.......

http://www.autoshop101.com/forms

#1416-11-2011 19:38:58

Re: Can I ask a question please.....(Speedo woes)

tea then back outside methinks

#1516-11-2011 19:49:35

Re: Can I ask a question please.....(Speedo woes)

Icon - Post link Paul1566 wrote:

If the converter was fubar surely the ecu would not sense a fault as the fault would be on the input to the speedo not the input to the ecu ????
Only had a very quick skim of that info Vince posted, but it looks like the signal is likely processed in the cluster before it reaches the ECU, so if that has died, become disconnected, (or it may even just be shonky connections on the cluster), the ECU may well be receiving nowt.

#1616-11-2011 20:17:44

Re: Can I ask a question please.....(Speedo woes)

Ok steak chips and peas done, been out and removed it again to try.
Turn it slowly and it goes from 0 to 12 to 0 to 12 etc etc
If you get twelve and stop it stays on 12 till you turn a wee bit more.
rotate constantly with finger and it gives 6v constant.

Read the pdf on MRE sensors and as Matt says it appears to go to the cluster first.
Also shows square wave of 0-12-012-0-12 so seems ok.
Will have to remove dash and find converter and put back to original to see if that cures it.

Kirsty's on so that will have to wait...... tongue

#1716-11-2011 21:33:48

Re: Can I ask a question please.....(Speedo woes)

Double check all of the connections to the panel, clean them and check for any dodgy solder joints before you remove that convertor. Best to remove that as a last resort.

#1817-11-2011 08:30:22

Re: Can I ask a question please.....(Speedo woes)

Well bugger me sideways and call me shirley, its only fooking working again.

Threw some tools in a bag to start the dash removal at lunchtime, got halfway up the road, looked down and it was working.  big_smile
Fine all the way to work, even seemed to be moving smoother than before (my imagination)
Will see if its still working tonight on me way home.

Anyway thanks for the advice guys

#1917-11-2011 09:18:01

Re: Can I ask a question please.....(Speedo woes)

May have have been a dirty connection in the plug, and all the buggering around has made a better connection.

Or whatever wire is iffy behind the dash is touching again now.

big_smile

#2017-11-2011 09:27:14

Re: Can I ask a question please.....(Speedo woes)

I will just keep threatening it with dashboard removal, that should keep it working......

Least i know i have a pulse from sensor and a supply to the plug.

#2117-11-2011 11:03:16

Re: Can I ask a question please.....(Speedo woes)

Nice one Shirley! you do realise that asking to be buggered sideways is not a good idea on this forum   yikes  yikes  GWH or Matt to name just  two may take you up on the offer infact there is probably a queue forming as I write this  devilish  devilish  devilish

#2217-11-2011 12:41:49

Re: Can I ask a question please.....(Speedo woes)

lol

I think you'll find that they're actually enroute to Tewkesbury already ...


whistle

#2317-11-2011 12:47:09

Re: Can I ask a question please.....(Speedo woes)

Better pedal faster cus i'm on me way up north....
Well i say north its only Mansfield......not really north, just northish........
Someone's bound to say its south of them therefore its not north..........
Taking celica so mrs can foot the fuel bill to see my parents.....result








Well it had to happen didn't it........  sad

So quick question, if i use the live supply pin 1 on the plug at the sensor end to inject a pulse (tap two wires together at a constat rate   bounce ) into pin 3, would this confirm the sensor is at fault if the speedo registers ?
Or has the sensor got a little man inside that produces a perfect square wave needed to make it work ?

Haven't got a square wave generator handy, gave it away years ago along with an ociliscope....

#2418-11-2011 18:57:47

Re: Can I ask a question please.....(Speedo woes)

You've confirmed the sensor is working, it's time to check the speedo head now. It may be just a loose multi-plug on the back of the cluster or a dry solder joint.

#2518-11-2011 19:44:13

Re: Can I ask a question please.....(Speedo woes)

Or the little man in the mouse wheel needs feeding... big_smile  big_smile
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