1999 V70 - Swapped transmission- codes retained by TCU?

JuliusC · Post by **JuliusC** » 12 Nov 2018, 18:29

I have been searching online and trying to find out if , after having the battery disconnected for a month while doing a transmission change ( AW 50-42 ) whether the codes generated by the failed original transmission causing a flashing arrow/ check engine warning on dash might still be retained. The failed transmission had water contamination and basically stopped functioning, installed a replacement (used ) known to be functioning and noticed the same warning on dash.

The vehicle goes into drive/ reverse and shifted well, although as the car is still uninsured I was only able to get it into second in the parking area so not able to fully check but it at least is working. Wondering if the TCU after being disconnected would still have those error codes? Also, as the transmission came from a 1998 S70 and the Volvo it went into is a 1999 V70 ( both NA ) is there any difference in the sensors on the transmission? I know the '98 uses Bosch components where the '99 is equipped with Denso.

I understand that both the ECU and TCU will be relearning to a degree, so far the car appears to be running alright. I guess I am hoping that perhaps there might be residual codes that need to be erased though supposedly disconnecting power for a period is supposed to do this.

Any help would be very much appreciated - I will not know if the transmission will go into overdrive/lockup until I get a permit. This is actually the second transmission as the original died due to coolant contamination so bought it cheap and unfortunately the first replacement transmission was stored for four years and somehow got some water inside, unknown to myself so when it failed I bought the second one, so far so good except for the flashing arrow/ engine light. It is in very nice condition and maintained by previous owner.

Since purchasing it earlier this year ( and only driving it once before the trans. went ) I have replaced the radiator, heater core ( was the original ), control arms, rear main seal, oil pan o rings, filters. I really hope it is something minor as it drives well.

Post by **precopster** » 12 Nov 2018, 23:28

I did an 850 auto into a 1999 about 4 years ago. The sensors are different and need to be swapped out. There are 2 speed sensors on the transmission.

JuliusC · Post by **JuliusC** » 12 Nov 2018, 23:38

What year was the 850? As the transmission I have is from a 1998 S70 there could be a compatibility issue just the same since it is a Denso system in the '99, I was going to swap them but did not find any information beforehand - 1995 and earlier 850 transmissions had one sensor in a different location apparently.

Post by **precopster** » 12 Nov 2018, 23:54

850 transmissions were the same as V70s and S70s until 1999 when the sensor system was replaced. Denso or Bosch is the engine computer: Temic is the TCM. They were all Temic TCMs but the low speed Canbus was introduced in 1999 requiring new speed sensors

If your donor transmission was from the same aspiration (turbo or non turbo) you won't have issues with the final drive ratio either

Post by **precopster** » 13 Nov 2018, 00:07

These are the exact codes i pulled from vida when using the wrong sensors on a 1999 V70 (apart from the psr code)

JuliusC · Post by **JuliusC** » 13 Nov 2018, 00:16

I checked the FCP Euro site and the speed sensor that goes to the multipin connector housing that also has the pnp switch connector is different, 1998and earlier part# is 3515266 whereas 1999 is 9496115.I guess that answers my question and thank you for confirming! The other sensor at the back side of the trans. has its own connector was recently replaced so will swap those today.

Hopefully this will rectify the issue as I assume as soon as the TCU was energized it recognized the wrong signal from the incorrect sensor. Thank you very much for your help!

Post by **precopster** » 13 Nov 2018, 15:28

No Problem. I believe that scan was taken after only one of the sensors was swapped
(not the one sharing the PNP connector)

I totally missed the location of the second one as I recall it was hidden under wiring

JuliusC · Post by **JuliusC** » 13 Nov 2018, 18:34

I am wondering about stored codes from the previous transmission - as soon as I had installed the second trans., connected the battery and turned the ignition to the run position all of the dash lights came on but the arrow was flashing, this before starting and driving the car.

I would think one would have to actually perform some driving in order for the TCU to pick up any faults which is why I think possibly it needs to be cleared I changed the two sensors to the correct ones and of course the flashing arrow/ engine combination is showing. Any thoughts?

ferocity02 · Post by **ferocity02** » 13 Nov 2018, 21:58

I had the battery disconnected for a few hours and the TCU code and associated flashing up arrow and check engine light went away.

Post by **precopster** » 14 Nov 2018, 03:29

With the right sensors as soon as you drive to over 20km/h the codes clear as the self-check occurs at speed; at least that's my recollection of how it cleared on my car.