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Speed sensor fault

Pete O

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Hi guys, I have a speed sensor fault (code 24) coming up. My speedo works fine & the code doesn’t come up immediately but by the time I hit top gear it is there. Just before it comes up it hesitates for a second then it comes on. It is also doughy & drinking fuel like it is going out of fashion when the engine light is on.
I have read some threads on it & am not sure if it is the sensor, the ecu or a wiring problem now?
Anyone help me out with what one could possibly be the culprit. I’m going broke buying fuel....

Cheers...........Pete.
 

MikeC

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Are you getting 12V at the speed sensor (pink/blue ?) power wire with the ignition on? Check the sensor earth (black/white ?) wire. I'd also check , break and clean with contact cleaner every connector between the speed sensor and the ECU.
 

Pete O

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Are you getting 12V at the speed sensor (pink/blue ?) power wire with the ignition on? Check the sensor earth (black/white ?) wire. I'd also check , break and clean with contact cleaner every connector between the speed sensor and the ECU.
Thanks MikeC, I only got home yesterday morning so I will check that out today. I had a quick feel under the car on my way home & it was actually loose & covered in oil so I tightened it as much as I could & kept going but it was still the same. I’ll give it a good clean up today & do the connectors as well.

Cheers..........Pete.
 

MikeC

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Did you pull the ECU fusible link for 30 seconds to reset it?
 

MikeC

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If it came back without the car moving it's probably the wiring - the control system was doing communication checks with it's sensors. I'd check the wiring , if that's good it's time to have a look at the sensor.
 

Pete O

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If it came back without the car moving it's probably the wiring - the control system was doing communication checks with it's sensors. I'd check the wiring , if that's good it's time to have a look at the sensor.
First time today I done about 25k before the car coughed & spluttered then the light came on. Then I stopped after about 2 hrs & when I took off it came on again after about 2 km.
 

MikeC

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First time today I done about 25k before the car coughed & spluttered then the light came on. Then I stopped after about 2 hrs & when I took off it came on again after about 2 km.
Looks like it's an intermittent fault, probably not the sensor could be wiring. According to my manual there are ways of testing the sensor that involve installing temporary resistors then turning it by hand and watching the voltage fluctuate wit a multimeter- I've never done it and the method is not simple to describe.
Is the square drive in the center of the sensor engaging fully?
 

Pete O

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Looks like it's an intermittent fault, probably not the sensor could be wiring. According to my manual there are ways of testing the sensor that involve installing temporary resistors then turning it by hand and watching the voltage fluctuate wit a multimeter- I've never done it and the method is not simple to describe.
Is the square drive in the center of the sensor engaging fully?
Oh goody, just what I need an intermittent fault that will take me forever to find, lol. I haven’t had the sensor out yet as I haven’t had time, I’ve parked the ute up until I get a minute to look at it. I’m in the middle of shifting house & don’t have any spare time. Bad time for the ute to start playing up.
 

MikeC

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Oh goody, just what I need an intermittent fault that will take me forever to find, lol. I haven’t had the sensor out yet as I haven’t had time, I’ve parked the ute up until I get a minute to look at it. I’m in the middle of shifting house & don’t have any spare time. Bad time for the ute to start playing up.
The joy of owning an old Holden. I have an instrument cluster that's falling apart and a missus that wants to know why the old Statesman is cluttering up the carport.
 
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