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Speedometer Not Working



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Clint Young

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!

Bitter

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.

Clint Young

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.

Bitter

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.

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.

Clint Young

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. default_smile

Bikeman982

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.

JeffG

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...

Bitter

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

Clint Young

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.

Bitter

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.

Bikeman982

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.

 

 

Bitter

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...

 

 

Clint Young

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. default_smile 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.

Bitter

hmm, so is your odometer off now?

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

Clint Young

hmm, so is your odometer off now?

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

I might just do that.. I know on my other car I would manually roll the numbers. I just wrote down the original mileage and the new mileage on a piece of paper so I could calculate the actual mileage if needed. I'm sure it probably won't matter anyways.. I'm going to drive this thing until the wheels fall off! at 225,000 miles, it is still running strong! (But it sure would be nice to read the actual mileage and not have to reference my piece of paper.. when I end up losing it! lol)

Bitter

also, theres legal issues of having the odometer showing the correct milage, for example if it were in an accident and was to be totalled and they needed to calculate the value to write you a check, the wrong milage could either get you less money or get you investigated for fraud.

Clint Young

Noted. I'm certainly not looking to cheat anybody here by any means. Purchased this car brand new in 93', and just wanted to get it back up to par. default_smile

Bikeman982

In the old days - people disconnected their spedometer cable to keep the cars miles low. Sometimes they tampered with the odometer and turned the miles back (until they made them more tamper-proof). Totally dishonest, but never-the-less, they did it.

Clint Young

In the old days - people disconnected their spedometer cable to keep the cars miles low. Sometimes they tampered with the odometer and turned the miles back (until they made them more tamper-proof). Totally dishonest, but never-the-less, they did it.

Yeah, a guy down the street from me while I was a kid did that. My dad owned an automotive repair shop and he constantly tried to get my dad "into the ring" with him. He refused. While I thought their pool house and cars were cool as a kid, I guess there is a reason he is in prison now. default_smile And my dad is retired with a squeaky clean record.

Bikeman982

In the old days - people disconnected their spedometer cable to keep the cars miles low. Sometimes they tampered with the odometer and turned the miles back (until they made them more tamper-proof). Totally dishonest, but never-the-less, they did it.

Yeah, a guy down the street from me while I was a kid did that. My dad owned an automotive repair shop and he constantly tried to get my dad "into the ring" with him. He refused. While I thought their pool house and cars were cool as a kid, I guess there is a reason he is in prison now. default_smile And my dad is retired with a squeaky clean record.

I take it he was in the auto-selling business and he was less than scrupulous (the guy down the street).

 

 

Clint Young

Yes, he rolled back odometers on cars. I would imagine there were several unhappy people out there in the world. He actually went to jail for it the first time, but didn't learn his lesson. I think the second time must have done the trick. Knowing about his "endeavors" has always made me cautious about mileage on vehicles.

Bikeman982

Yes, he rolled back odometers on cars. I would imagine there were several unhappy people out there in the world. He actually went to jail for it the first time, but didn't learn his lesson. I think the second time must have done the trick. Knowing about his "endeavors" has always made me cautious about mileage on vehicles.

It is harder to roll back odometers in the new cars.

Bodger2

Hi guys this my first post here at Corolland, but I have been reading here for sometime now. I was reading all the back pages and I final stumble across this thread and it seems to be the exact same problem I am having with my 93 rolla as well. The trip and odo are working fine but the speedo usually goes to 40 to 60 KM (Canada) and at highway speeds it actually goes the opposite way from 60 Km and reads 30 to 40 Km when I'm actually driving 90 KM.

It's nice to see someone actually post how they fixed there problem so others can learn from it. I a very hopefull now that this will solve my problem to. I didn't want to replace VSS for no reason.

Thanks to the OP. And thanks to Fishexpo101 and Bitter. You guys provide a lot of useful info here I have noticed.

Had the same problem 96 Toyota Corolla.  Got a used cluster from junkyard but now odometer works and speedometer doesn’t.