New Transmission Shifting Issue

Post by **JRL** » 11 Jan 2011, 21:07

Which is what I said, he needs a 99 TCU but a 99 TCU will not work in a 98 at all

Post by **jimmy57** » 11 Jan 2011, 22:15

No, he needs the speed sensors that work with the 98 TCM and the rest is fine. The transmission hardware changes are limited to the speed sensors. The other electrical parts and valve body have the same part numbers for 98 and for 99.
The trans hardware exclusive of sensors is the same, only the TCM is different. The CAN TCM is also smarter and they axed the S/E/W switch and used software analysis of throttle to decide the sport or economy strategy but the upgraded TCM uses the newer digital sensors. Volvo fell in love with magnetic resistive sensors in 99 and spread them around. CMP sensor, ABS wheel speed sensors, and the speed sensors on trans all switched over to those. That style sensor has a weak magnet and won't hold metal filings and has less chance of getting erratic signals from metal filing "fuzz".
I've overhauled early and late AW 50-42's and there is no difference in the internal hard parts or friction parts.

GEM-Massachusetts · Post by **GEM-Massachusetts** » 13 Jan 2011, 10:27

First, let me thank you guys for your responses to my problem. The original transmission (“98 trans”) failed on Halloween night. 98 trans has 178k miles on it. Car was steered to the side of the road; it would not go forward or reverse. I took the car on a trailer to a local repair garage that focuses on Volvos. The owner has previously worked on the car for me and seems to be very knowledgeable about Volvos. He said the trans was broken and perhaps the viscous coupler was damaged as well. He said that because the car was 13 years old with 178k miles, it was not cost effective to have him fix the car. Turns out that my son got the car stuck in mud the night before and called a buddy with a truck to pull him out. After torturing myself by looking around with my son for another used car without finding anything decent, I decided to really torture myself and teach my son a lesson by fixing the car ourselves. As I kid I worked extensively on Chevys and did a complete ground up restoration of a 1970 Camaro, that I still own. Needless to say, a 1970 Camara is no 1998 Volvo v70xc. As mentioned previously, I got the new replacement transmission (“new trans”) from another nearby Volvo mechanic. I was told that the new trans came from a 99 Volvo v70xc that was parted out, in part due to a failed fuel pump. The new trans seller stated that it would work properly in the 98. Also, I still have the 98 trans.

Additional road test info:

In “Winter” mode new trans shifted into “D” gear, car accelerates in what seems to be 2 or 3rd. As vehicle speeds increases, new trans auto shifts into next gear (3rd or 4th).

In winter mode with new trans shifted into “L” gear (forward gear options D, 3 & L), car accelerates in what clearly seems to be 1st gear. This is based on vehicle acceleration response and engine RMP. As car travels, upon manual shifting from “L” into “3” gear, new trans shifts into 2nd gear. The actual gear change from 1st to 2nd seems to happen independently of the engine rpm. Such that if shifted from 1st to 2nd at 2k rpm, gear change seems to occur at about 3k rpm. As vehicle speed further increases, upon manual shifting from “3” into “D”, trans shifts into 3rd. Further vehicle speed increase up to 70 mph causes no further trans up shift (meaning that new trans does not shift into 4th gear)

Attached is a picture of the 98 trans. The wiring connector labeled as “B” in my picture is comprised of 4 separate wiring pin connectors. The VADIS transmission diagram identifies the Temperature sensor, the Starter Inhibiter Switch & Tachometer sensor. The last pin connector identified as #15 in the VADIS transmission diagram is not further identified in the VADIS part list. The wiring connector labeled as “A” in my picture is a single wiring connector. VADIS simply identifies it as a “sensor”. Can you enlighten me as to what the unidentified sensors are? Also, jimmy57, can you further direct me as to which sensor is the “speed sensor”? With your input, I’ll swap the “old” speed sensor for the “new” one. Thanks.

Post by **jimmy57** » 13 Jan 2011, 10:55

A in the photo is the vehicle speed sensor.
The input shaft speed sensor is below the round servo cylinder below and next to the trans connector in your photo.
To verify the suspicions use an ohmmeter and get reading between the two pins on the VSS of the trans in photo and compare to the readings obtained from the same part in trans you put in car.
The VSS is easy to change since it is held by one bolt and has a easy to access connector but you have to pull the trans connector apart and separate the segments to change the ISS (tachometer sensor, though it is not for the tachometer but that is probably the Swedish technical translator program term for a shaft speed sensor).

GEM-Massachusetts · Post by **GEM-Massachusetts** » 13 Jan 2011, 13:12

Thanks for the input jimmy57. I am getting a reliable meter to check the resistance values of the 98 and 99 Vehicle Speed Sensors as you directed. How much difference in resistance should I expect between the 98 and 99 VS Sensors? Also, do I understand you correctly that you suggest that both the VSS and the Tachometer Sensor (aka Input Shaft Speed Sensor) need to be changed? I have notated the ISS Sensor in the attached photo. Thanks.

Post by **jimmy57** » 13 Jan 2011, 13:50

The spec is 300-600 on the 98 down and the 99-00 shows can't be tested for the input speed sensor but shows the same value for the VSS for both year ranges. The magnetic resistive type will have a high impedance. Probably tens of thousands of ohms. The real test for the input sensor is that they are different which the specs say they should be. The specs say the input sensor is different as well as different part numbers in volvo's parts info. The Specs are the same for VSS but it also carries a different part number. VSS may have had a change just in its connector or wire length.
Does the connector info you have detail which pins are which?

You have them ID'd correctly on the pic. The item you label "Sensor" is the wiring pass-through for solenoid wires going to valve body.

GEM-Massachusetts · Post by **GEM-Massachusetts** » 13 Jan 2011, 17:48

I took the 98 trans sensors off. Both the Vehicle Speed Sensor (“VS”) and the Input Shaft Speed (“ISS”) Sensor (aka Tachometer Sensor) were measured at 400 ohms. In addition to swapping the 99 trans VS and ISS Sensors for the 98 trans VS and ISS Sensors, should I consider swapping the Starter Inhibitor Switch as well. I am in the process of removing the 99 trans VS and ISS Sensors. Thanks.

Post by **jimmy57** » 13 Jan 2011, 17:52

The part numbers for the Start inhibitor sw. is the same for both in parts listings so I'd use the one with fewer miles and assumed less wear.

GEM-Massachusetts · Post by **GEM-Massachusetts** » 13 Jan 2011, 20:01

The 99 trans Vehicle Speed Sensor and Input Shaft Speed Sensor both measured 1,400 ohms. So I'm going to install the 98 trans VSS and ISSS into the installed 99 trans. Thanks for the help.

GEM-Massachusetts · Post by **GEM-Massachusetts** » 13 Jan 2011, 22:51

It is with great pleasure that I report we have achieved, in the words of Borat, "Great Success!" To jimmy57: you sir are a gentleman and a scholar. I swapped the VSS and ISSS from the old 98 trans into the transplanted 99 trans. A test drive seems to indicate complete success. The car, in normal "E" mode, automatically shifted smoothly through 1st to 4th gear. A hard start on a steep snow packed incline seems to indicate a problem with the viscous coupler. However, there appears to be no issue during normal driving. Thank you again jimmy57.