Transmission OD intermittent issue (Solved!!) (1 Viewer)

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That's what I do (sensor), at this point. But I would have done more than just look at wires. So if sensor doesn't do the trick. Revisit the wires, wire housing blocks, etc., A/T back to CPU.
I honestly don't know how to do much more than look that wires.

I received the sensor and will install later today. 🤞 fingers crossed!

Will the P0715 code clear itself with new sensor, or should I clear before test driving?
 
Update: I still lost 4th. I replaced both transmission revolution sensors with new ones last night. I drove the same loop and at about 24 miles I lost 4th. Like last time, my OBD2 reading for MPH went funky the moment it happened (70mph was showing 26mph). I cleared the CEL before I drove. During drive, CEL did not come on.

Additional piece of interesting info. is that after driving about 35 miles without OD, randomly 4th came back! For the last 10 miles, I had 4th again. I don't know why.


What should the transmission temp be? On my OBD2, it was showing around 170-177 on hwy without OD.
 
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That temp is fine. I would pull the battery for a good long time, if you haven't, and then reconnect it and test drive again.
 
Update: I still lost 4th. I replaced both transmission revolution sensors with new ones last night. I drove the same loop and at about 24 miles I lost 4th. Like last time, my OBD2 reading for MPH went funky the moment it happened (70mph was showing 26mph). I cleared the CEL before I drove. During drive, CEL did not come on.

Additional piece of interesting info. is that after driving about 35 miles without OD, randomly 4th came back! For the last 10 miles, I had 4th again. I don't know why.


What should the transmission temp be? On my OBD2, it was showing around 170-177 on hwy without OD.
Whereas your 170-177f A/T temp is fine. It's a tiny bit high for a short causal drive, unless a very hot sunny day. Going back to earlier post: "2) Coolant system is working well. "The ECT goes above 130 very quickly and then stays in the 185-195 range for duration of drive (ambient temp 105f and going 60-70mph on highway)." If simular day, than AT temp is fine.

For a 2000 with condenser fan. You're ECT seem a to be running a tad hot. I see 2000-02 run 184-187F all day long, with OAT 100F full sun. Only touch 190F for a moment then backing down. Just observation not your A/T OD issue related.

Seems you have some improvement, but still issue with OD. Keep driving see if improves any more or clears. If not, then point if problem persist. You should take to "good" transmission shop.
 
Hey Guys, I just got back from a week long vacation. So I am back to looking at next steps. I think the next step is to check for electrical shorts? How does one go about doing this? I don't know where to start. Do I need to pull off the plastic tubing sheath that covers the transmission wires?
 
I think the issue is fixed! BAD WHEEL SPEED SENSOR!

After figuring out which sensors were giving me a speed reading on my OBD2 through unplugging different sensors on transmission, the final option was wheel speed sensors and it turned out this is where the speed was being derived from. Jacked up 1 rear wheel while in accessory mode, spun it hard and sure enough the speed value on my app moved.

Then, using the FSM, I wrote down the resistance value range for speed sensors. Note- fronts and rears have different values. Fronts and driver rear were all in spec. THEN, I looked at passenger rear and the wire was almost completely gone. Only a couple strands holding it together. Below is a photo.

Also, the way the rear passenger wiring is done, it is a REALLY TIGHT fit with strain on wire. Other 3 seem totally fine, no strain. To be fair, this is probably original sensor and still had 335k before starting to short out.

As for replacing, no local dealer had sensor in stock and dealership price was like $330. I went to AutoZone and picked up a duralast branded sensor. I happily discovered that the "duralast" speed sensor was made in Japan with Aisin on the sensor. $130 for Japanese made sensor, most likely near OEM quality.

Since changing sensor, I have driven about 250 miles of varied driving on specific routes that have consistently "triggered" losing 4th. So far, no issues at all. I will be doing a 600ish mile road trip to Northern California next week, so that will be the final test and I will report back.

Thank you to everyone who has posted and sent messages trying to help. This issues has turned into an opportunity for me to learn much more about this 100 series.

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I think the issue is fixed! BAD WHEEL SPEED SENSOR!

After figuring out which sensors were giving me a speed reading on my OBD2 through unplugging different sensors on transmission, the final option was wheel speed sensors and it turned out this is where the speed was being derived from. Jacked up 1 rear wheel while in accessory mode, spun it hard and sure enough the speed value on my app moved.

Then, using the FSM, I wrote down the resistance value range for speed sensors. Note- fronts and rears have different values. Fronts and driver rear were all in spec. THEN, I looked at passenger rear and the wire was almost completely gone. Only a couple strands holding it together. Below is a photo.

Also, the way the rear passenger wiring is done, it is a REALLY TIGHT fit with strain on wire. Other 3 seem totally fine, no strain. To be fair, this is probably original sensor and still had 335k before starting to short out.

As for replacing, no local dealer had sensor in stock and dealership price was like $330. I went to AutoZone and picked up a duralast branded sensor. I happily discovered that the "duralast" speed sensor was made in Japan with Aisin on the sensor. $130 for Japanese made sensor, most likely near OEM quality.

Since changing sensor, I have driven about 250 miles of varied driving on specific routes that have consistently "triggered" losing 4th. So far, no issues at all. I will be doing a 600ish mile road trip to Northern California next week, so that will be the final test and I will report back.

Thank you to everyone who has posted and sent messages trying to help. This issues has turned into an opportunity for me to learn much more about this 100 series.

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Great and thanks for posting cure. But strange you didn't see a CEL with wheel speed sensor DTC. Nor dash light-up and ABS/ATRC/VSC shut down.

When we first turn on IG key. System goes through selftest mode. We see all dash warning & indicator lights come on for a few seconds. Do you?
 
I think the issue is fixed! BAD WHEEL SPEED SENSOR!

After figuring out which sensors were giving me a speed reading on my OBD2 through unplugging different sensors on transmission, the final option was wheel speed sensors and it turned out this is where the speed was being derived from. Jacked up 1 rear wheel while in accessory mode, spun it hard and sure enough the speed value on my app moved.

Then, using the FSM, I wrote down the resistance value range for speed sensors. Note- fronts and rears have different values. Fronts and driver rear were all in spec. THEN, I looked at passenger rear and the wire was almost completely gone. Only a couple strands holding it together. Below is a photo.

Also, the way the rear passenger wiring is done, it is a REALLY TIGHT fit with strain on wire. Other 3 seem totally fine, no strain. To be fair, this is probably original sensor and still had 335k before starting to short out.

As for replacing, no local dealer had sensor in stock and dealership price was like $330. I went to AutoZone and picked up a duralast branded sensor. I happily discovered that the "duralast" speed sensor was made in Japan with Aisin on the sensor. $130 for Japanese made sensor, most likely near OEM quality.

Since changing sensor, I have driven about 250 miles of varied driving on specific routes that have consistently "triggered" losing 4th. So far, no issues at all. I will be doing a 600ish mile road trip to Northern California next week, so that will be the final test and I will report back.

Thank you to everyone who has posted and sent messages trying to help. This issues has turned into an opportunity for me to learn much more about this 100 series.

View attachment 3766257

View attachment 3766258

Do you happen to have the Duralast part number for the sensor you used? I'm trying to look it up on AZ's site but it appears to be down at the moment.
 
Hi All,

Sorry for late reply.

1. All the dash lights do indeed come on when turning on car. No CEL or ABS/Vsc. I do not really know why. My best guess is that the sensor was shorting out but I do not know how the computer interprets the wheel speed sensors or maybe averages the speeds out? If so, perhaps the sensor/wire was still providing information (to some small degree) and therefore not totally "dead". Perhaps if it was totally dead, it would have triggered a warning light? When the issue presented, the speed reading derived from OBDII did NOT go to zero, rather it would not read past 26 mph, and subsequently that speed is not high enough for 4th gear to engage.

2. Duralast Part Number for Passenger Rear Wheel Speed Sensor: SU8429
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