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Speedometer Not Working


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#1 Clint Young

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Posted 24 August 2006 - 08:46 PM

Hello - I am looking for some input here. The situation is as follows:

The speedometer does not work on my 1993 Toyota Corolla DX 1.8L. It stays at 0Mph until probably 40-50 Mph and then shoots up to about 67 and stays there whether you go 80 or 50. Another strange thing is that the clock hours count 1,2,3,4,5...12. And keep cycling. I was told that the circuit that the clock and the speedo run off of is completely separate, but they both went out at almost the exact same time. (if not, within a day or so).

Troubleshooting performed is as follows:

Today I removed the speed sensor from the transmission. The gear wheel on it moves as I think it should feel. There is no wear on the gear, nor is there any wear on the gear inside of the transmission. I removed the insturnment cluster today and looked at all the connections. They didn't appear to be dirty, but I used a Q-Tip and some Alcohol and cleaned all the connections. I removed the front cover of the housing and the speedometer moves as it should (I can move it to wherever, and it moves back down at a set pace/resistance.)

I am wondering what the problem might be? It sounds like a potential ground somewhere to me, but I cannot be sure since I don't have such detailed wiring diagrams to diagnose this.

Has anybody heard of anything similar, or have any recommendations as to what to try next? I really appreciate your input. Thanks!

#2 Bitter

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Posted 24 August 2006 - 09:38 PM

your clock and speedo issue could be seperate. it could be the speedo sensor in the trans, ontop of the unit. its 2 red wires.

#3 Clint Young

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Posted 24 August 2006 - 09:55 PM

your clock and speedo issue could be seperate. it could be the speedo sensor in the trans, ontop of the unit. its 2 red wires.


Is it possible to test the speedo sensor with a multimeter? Found autozone has it, but it is $189. I'd like to have it 100% narrowed down before making the purchase. Thanks for your response.

#4 Bitter

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Posted 24 August 2006 - 10:13 PM

yes, but im not sure of the test procedure. a simple test of the parts resistance (should be more than 0 and less than infinite) could give you a basic idea. i'd suggest pulling one from a junked car with the same engine/trans.

#5 fishexpo101

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Posted 24 August 2006 - 10:48 PM

You should be able to measure the voltage across the pins on the speed sensor. You can backprobe the sensor (need 12V power to measure the sensor). If you stare at the pins, sensor oriented with bolt hole on top, pins should be numbered 3 -2 -1 from left to right. Pin 1 is source (+12V), Pin 2 is ground, and pin 3 is signal. Probe pins 2 and 3 and measure the voltage as the shaft is rotated - should go from 0V to source voltage four times for every full revolution of the shaft.

#6 Clint Young

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Posted 24 August 2006 - 10:53 PM

You should be able to measure the voltage across the pins on the speed sensor. You can backprobe the sensor (need 12V power to measure the sensor). If you stare at the pins, sensor oriented with bolt hole on top, pins should be numbered 3 -2 -1 from left to right. Pin 1 is source (+12V), Pin 2 is ground, and pin 3 is signal. Probe pins 2 and 3 and measure the voltage as the shaft is rotated - should go from 0V to source voltage four times for every full revolution of the shaft.



Thanks! I'll give that a go here in the next day or so. :)

#7 Bikeman982

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Posted 25 August 2006 - 12:43 AM

Hello - I am looking for some input here. The situation is as follows:

The speedometer does not work on my 1993 Toyota Corolla DX 1.8L. It stays at 0Mph until probably 40-50 Mph and then shoots up to about 67 and stays there whether you go 80 or 50. Another strange thing is that the clock hours count 1,2,3,4,5...12. And keep cycling. I was told that the circuit that the clock and the speedo run off of is completely separate, but they both went out at almost the exact same time. (if not, within a day or so).

Troubleshooting performed is as follows:

Today I removed the speed sensor from the transmission. The gear wheel on it moves as I think it should feel. There is no wear on the gear, nor is there any wear on the gear inside of the transmission. I removed the insturnment cluster today and looked at all the connections. They didn't appear to be dirty, but I used a Q-Tip and some Alcohol and cleaned all the connections. I removed the front cover of the housing and the speedometer moves as it should (I can move it to wherever, and it moves back down at a set pace/resistance.)

I am wondering what the problem might be? It sounds like a potential ground somewhere to me, but I cannot be sure since I don't have such detailed wiring diagrams to diagnose this.

Has anybody heard of anything similar, or have any recommendations as to what to try next? I really appreciate your input. Thanks!



Interesting problem. I don't think speedometer and clock problems are connected.
Speedometer may have to do with sensor, wiring or even your ECM.
The clock is probably just gone bad.

#8 JeffG

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Posted 28 August 2006 - 07:18 PM

Does the 93 gen have an electronic spedo? My 92 had a mechanical sepdo and it quit working. I took off the cable and spun it with a cordless drill to see if it spun... Nope.. So i just followed the spedo cable back untill i found a short section that was broken...

Edited by JeffG, 28 August 2006 - 07:18 PM.

#9 Bitter

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Posted 28 August 2006 - 07:30 PM

93 is electronic. the speedo and odometer are in the same module, does the odometer work?

#10 Clint Young

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Posted 28 August 2006 - 07:34 PM

Yes, he definitely is correct. Electronic speedometer. Interesting that you would bring this up, because it has been on my mind as well. The odometer/tripometer work just fine, just the speedo does not function. Is it something else that runs the odometer? I am going to try and get a replacement speed sensor to see if that will do it.

#11 Bitter

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Posted 28 August 2006 - 09:57 PM

well i think the VSS (vehicle speed sensor) feeds signal to the speedo and odometer, since theyre in the same unit, but it wouldnt hurt to test the sensor and check the wiring.

#12 Bikeman982

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Posted 28 August 2006 - 11:53 PM

well i think the VSS (vehicle speed sensor) feeds signal to the speedo and odometer, since theyre in the same unit, but it wouldnt hurt to test the sensor and check the wiring.

I think it uses the same sensor, but splits the signal for the speedometer and the odometer.

#13 Bitter

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Posted 29 August 2006 - 12:42 PM


well i think the VSS (vehicle speed sensor) feeds signal to the speedo and odometer, since theyre in the same unit, but it wouldnt hurt to test the sensor and check the wiring.

I think it uses the same sensor, but splits the signal for the speedometer and the odometer.

i think i hear an echo in here...

#14 Clint Young

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Posted 29 August 2006 - 06:34 PM

FIXED!!!

Replaced the Speedometer guage cluster and all is well!

Went by the junkyard today, and lucky for me, they happened to have 1 Toyota Corolla sitting there. It was a 1993 exactly like mine! :) Stripped the rear taillight electrical harness, rearview mirror, speed sensor, guage cluster, cigarette lighter, strut tower dust covers and a window knob to roll it down. :) Pretty good haul when I was there. Now the only thing I need to make this car complete again is a replacement clock and antenna.

Thanks so much for all your help! Much appreciated.

#15 Bitter

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Posted 29 August 2006 - 08:48 PM

hmm, so is your odometer off now?

you can roll it to your correct mileage by turning the trip odometer with a small implament

Edited by Bitter, 29 August 2006 - 08:48 PM.