Info: Transmission Speed Sensor on 01-02+ (and possibly 99-00) and limp mode

lawrencium265 · Post by **lawrencium265** » 01 Feb 2022, 09:18

I had somewhat of a difficult time figuring out that the sensor was bad, which sensor it was, and how to find a replacement.

My 01 V70 XC was going into limp mode (- instead of D on the dash and stuck in 3rd gea and "service transmission" message) the tcm had a code for the input speed sensor. Looking at the live data showed that it was working. I checked the sensor resistance through the wiring and it was in spec. When I drove the car the signal would blip to zero on occasion. I went back and looked at the sensor and pulled the rubber boot back and saw that the potting/epoxy where the wires go into the sensor was cracked.

I decided to replace the sensor, but they have been superseded by a different part. The original sensors come with the wires attached so you would need both sensors. They look like the older 99' sensors, but have a different style of harness connected to them.

The new option is two separate sensors and a new harness to plug them in and into the 4 pin connector in front of air box which is about $200 (30713724) . I decided to do some digging and found that there is a Nissan sensor (319358Y000) that is physically identical to the new style green Volvo sensor (30713952). There is also an even cheaper black variant of the Nissan sensor, I didn't try this one, but they are only around $10 each. I decided to buy one green aftermarket Nissan sensor and one Volvo sensor to see what the difference is.

When I ohmed the sensors the Nissan sensor was nearly identical to my old sensor, the new style Volvo sensor has a diode in it, it would only show resistance in one direction.

The magnetic polarity between the old sensor and both the Nissan and Volvo sensor are opposite, which i though was odd.

I managed to find aftermarket connectors that work with these sensors they're cheap if you look for them under "Lexus Pontiac Toyota speed sensor connector"

When I wired them up neither sensor worked at all, but I had a different code with the new Volvo sensor, it was "missing" that made me think about it's directionality and the difference in magnetic polarity, so I switched the wires and it worked successfully. I went ahead and replaced the output sensor with the Nissan one and it works too and it hasn't caused any faults yet, but I only fixed it yesterday, I'll report back here if it does.

Post by **xHeart** » 01 Feb 2022, 09:35

lawrencium265 wrote: ↑01 Feb 2022, 09:18 I had somewhat of a difficult time figuring out that the sensor was bad, which sensor it was, and how to find a replacement.

My 01 V70 XC was going into limp mode...

^it would mean sensor is working, unless someone says otherwise; cutting off fuel supply.
Is there a fault code?

lawrencium265 · Post by **lawrencium265** » 01 Feb 2022, 09:44

The code was TCM-0023, the fault was intermittent. I found drive the car for twenty minutes and then it would jerk and go into limp mode, then I could clear the codes and it wouldn't chime back immediately. It was only looking at the data graph while driving where I saw the input speed sensor go to zero for a split second.

Post by **xHeart** » 01 Feb 2022, 11:28

lawrencium265 wrote: ↑01 Feb 2022, 09:44 The code was TCM-0023, the fault was intermittent. I found drive the car for twenty minutes and then it would jerk and go into limp mode, then I could clear the codes and it wouldn't chime back immediately. It was only looking at the data graph while driving where I saw the input speed sensor go to zero for a split second.

Relevant, may be: viewtopic.php?f=9&t=71624

lawrencium265 · Post by **lawrencium265** » 01 Feb 2022, 11:45

After replacing the sensors the problem went away, the car shifts fine and firmly through so the gears. I just wanted to make a thread clarifying that there are options for sensor replacement, especially on earlier models where the manufacturer option is $200+. Buying two aftermarket sensors and connectors is about $65.

Post by **firstv70volvo** » 01 Feb 2022, 12:25

lawrencium265 wrote: ↑01 Feb 2022, 09:18 I had somewhat of a difficult time figuring out that the sensor was bad, which sensor it was, and how to find a replacement.

My 01 V70 XC was going into limp mode (- instead of D on the dash and stuck in 3rd gea and "service transmission" message) the tcm had a code for the input speed sensor. Looking at the live data showed that it was working. I checked the sensor resistance through the wiring and it was in spec. When I drove the car the signal would blip to zero on occasion. I went back and looked at the sensor and pulled the rubber boot back and saw that the potting/epoxy where the wires go into the sensor was cracked.

I decided to replace the sensor, but they have been superseded by a different part. The original sensors come with the wires attached so you would need both sensors. They look like the older 99' sensors, but have a different style of harness connected to them.

The new option is two separate sensors and a new harness to plug them in and into the 4 pin connector in front of air box which is about $200 (30713724) . I decided to do some digging and found that there is a Nissan sensor (319358Y000) that is physically identical to the new style green Volvo sensor (30713952). There is also an even cheaper black variant of the Nissan sensor, I didn't try this one, but they are only around $10 each. I decided to buy one green aftermarket Nissan sensor and one Volvo sensor to see what the difference is.

When I ohmed the sensors the Nissan sensor was nearly identical to my old sensor, the new style Volvo sensor has a diode in it, it would only show resistance in one direction.

The magnetic polarity between the old sensor and both the Nissan and Volvo sensor are opposite, which i though was odd.

I managed to find aftermarket connectors that work with these sensors they're cheap if you look for them under "Lexus Pontiac Toyota speed sensor connector"

When I wired them up neither sensor worked at all, but I had a different code with the new Volvo sensor, it was "missing" that made me think about it's directionality and the difference in magnetic polarity, so I switched the wires and it worked successfully. I went ahead and replaced the output sensor with the Nissan one and it works too and it hasn't caused any faults yet, but I only fixed it yesterday, I'll report back here if it does.

When I checked these sensors with the older style harness where the two sensors are hard-wired to the 4 pin connector they were tested using the diode setting on the meter because they're active type sensors with polarity, not a single resistance in both directions. With the older ones hard-wired in and if you don't mind splicing in a replacement sensor these sensors are easy and cheap to get from the salvage yards. In my opinion getting a used genuine OEM sensor is better bet than a $10 aftermarket sensor although it's good to know there's an inexpensive option available that works if funds are tight. Always appreciate someone like yourself that does some experimenting and finds an alternative that works. The input shaft and output shaft speed sensors are identical as far as I can tell and they don't go bad very often.

lawrencium265 · Post by **lawrencium265** » 01 Feb 2022, 12:40

I think the main problem with the hard wired sensors is that there isn't enough slack so if there is too much movement in the drivetrain from bad mounts the wires are getting pulled on. The output sensor on the back side didn't have this problem, but it also has a strain relief tie keeping the wire from getting pulled where it goes into the sensor. If you go to the junkyard and buy a sensor from a later car with the newer style and the harness is damaged you can at least grab one sensor and the connector instead of searching around for an old style sensor. It also looks like you could use the 99-00 input or output sensor and just cut the connector off, the only difference between the two is the wiring colors.