1996 850 Transmission Control Module (TCM) replacement

Post by **bmncw** » 15 Mar 2014, 06:29

Hi MVS

Last night my car was not showing any abnormal, but suddenly had these symptoms this morning:

1. Yellow arrow light does not show up when i press winter mode or i put the shifter to "3" position
2. Hard gear change from transmission when i put the shifter to "R" position
3. RPM drop too much when i put the shifter to "D" position
4. Can feel normal power when going reverse, but it feels like starting the car on 3rd gear when going forward (RPM raising fast but car move forward slowly)

I used VOL-FCR to search for a code, but the software gets no response from the transmission AW50-42LE.
The software can get response from ABS, SRS, Instruments, etc., but not from transmission.

I looked at my transmission control module (TCM), it says version 11.3, spending hours today to find that version on local parts shop with no luck, a friend of mine had version 1.3 so i tried to install the 1.3 TCM to replace my 11.3 TCM

Surprisingly, all of those symptoms mentioned above, disappear instantly:

1. Yellow arrow light now shows up when i press winter mode or i put the shifter to "3" position
2. Soft gear change from transmission when i put the shifter to "R" position
3. RPM acts normal when i put the shifter to "D" position
4. -not yet tested for driving reverse or forward and automatic shifting from low to top gear, will update later-

But the VOL-FCR software still cannot communicate with transmission.

My question is: is it safe to replace TCM version 11.3 with version 1.3 ? what will be the difference between those versions?

Many thanks!
Rizky

Post by **bmncw** » 15 Mar 2014, 08:18

update:

just few seconds after first start, the yellow arrow is flashing with green econo-mode light flashing as well.

drove the car for about 30 minutes including 15 minutes traffic jam and 15 minutes normal city driving.

shifting from 1,2,3 seems okay.
kickdown seems okay.

yellow arrow is still flashing.
tried to turn off the engine, start it again, yellow arrow still flashing.

mfagus · Post by **mfagus** » 15 Mar 2014, 08:27

Had same issue recently, check for codes. Replaced PNP and all good now.

Post by **bmncw** » 15 Mar 2014, 08:57

hi mfagus

i can not retrieve codes because the VOL-FCR software told me that the car is not responding when i check for transmission.

the car responds when i check abs, srs, etc.

Post by **bmncw** » 27 Mar 2014, 10:28

hopefully my experience would help others...

removed my original tcm 11.3, open it and few electrical components were burnt.

i installed tcm 1.3 couple of weeks ago, transmission worked fine but whenever it shift to 2nd gear from 1st, the yellow arrow blinked until i turn off the engine.

i ordered tcm 11.3 from ebay uk, removed tcm 1.3 then installed tcm 11.3 this morning (exactly the same version with the original from my car), problem solved.

thank you mvs.

Post by **jose456891** » 27 Mar 2014, 16:42

I would check for corrosion under the connectors of the computers. The only way the components would have burnt is if something was shorting the components.

Did anyone say water/rodent/hatch-job damage?

Its important to have that computer cover.

My 2 cents

Post by **Ozark Lee** » 27 Mar 2014, 16:46

VOL-FCR doesn't do powertrain codes unless you have Motronic 4.4. In all likelihood you have Motronic 4.3. A standard scanner should pull the transmission codes. If you can get them read that would eliminate much of the guesswork.

...Lee

Post by **esl_97_850_T5** » 28 Mar 2014, 13:21

VOL-FCR doesn't do powertrain codes unless you have Motronic 4.4. In all likelihood you have Motronic 4.3. A standard scanner should pull the transmission codes...

Lee,

I seem to be misreading your comment. Are you implying that:

a) Vol-FCR does not read DTCs from a '96-97 850's AW 50-42 that is paired with a Motronic 4.3, and
b) standard OBDII scanners do read DTCs from a '96-'97 850's AW 50-42 that is paired with a Motronic 4.3?

If yes to a), then see reference in next paragraph to my one or two AW 50-42 DTCs that are never reported using the standard OBDII emission diagnostics, but are reported by Vol-FCR Demo, even though I definitely have a Motronic 4.3.

If yes to b), then what are some examples? What are the Pxxxx Powertrain codes and what are the corresponding Volvo 3-digit DTCs? In my case, I have 1 (and sometimes 2) AW 50-42 DTCs that can be read by Vol-FCR v1.7 Demo (or even an ELM327 with a terminal emulator), but which have never in 1.5+ years been reported by several different standard OBDII scanners. I could easily believe that at least some auto transmission problems could be reported via the standard OBDII emission diagnostics. I've just never seen that yet on my '97 850 T5 (possibly due to my very limited 2 DTC experience).

From my perspective, it seems that transmission related DTCs for '96-97 850 AW 50-42 are best seen by a DIYer with limited funds via Vol-FCR (or similar software/scanners that can communicate using Volvo's special, ISO9141-2 based, keyword D3 B0 protocol), since those software/scanners access the AW 50-42 and see all its DTCs, not just the transmission related DTCs that might get reported via the legally mandated, standard OBDII emission diagnostics.

esl_97_850_T5

Post by **Ozark Lee** » 28 Mar 2014, 20:24

I'll defer all things ELM327 to you and take your word for it. You have obviously spent a lot more time with it than I have.

The fun for writing code went away for me a long time ago after writing PL-11 assembly code for a DEC PDP-11. Assembly language is monotonous but at least I had the instruction set. It seems that much of your work has been without the benefit of having a list of "questions" and the valid possible answers to correlate with the questions. My hat is off to you for your tenacity.

I do know that I can't get my VOL-FCR to talk at all to my Motronic 4.3 cars so I never even tried to query the automatic transmission. I do get valid transmission codes from my $29.00 Harbor Freight scanner and they have covered everything that I need to know.

...Lee

Post by **esl_97_850_T5** » 28 Mar 2014, 22:13

Lee, thanks for the info.

Wow! Memory lane. Been about 30 years since I've been around DEC PDP-11 Assembly. I did that for 7 years full-time. It was the most understandable, remember-able, and well-designed assembly language I've ever encountered. But I was glad to make the transition to C. Back to the present...

I now understand why you made the previous Motronic 4.3 statement and the standard scanner reading transmission codes statement. You're simply speaking from your own experience.

How many Motronic 4.3 cars do you have in the '96-'98 time frame? What year/model are the Motronic 4.3 cars that you can't talk to with Vol-FCR? Is it the '96 Platinum Edition Turbo? Does the '96 850 N/A have an M43 or M44? Does the '98 S70 T5 have an M43 or M44?

I understand that its impossible for Vol-FCR to talk with the Motronic 4.3 ECU itself. But I would expect that Vol-FCR should be able to talk to the COMBI, SRS, ABS, auto tranny, and Power Seats (if you have them) for any '96-'98 850/S70/V70/C70/XC70. I'm curious about this. I'll PM you on this, so the thread can stay more on the original topic.

Do you have any records of what transmission codes the $29 Harbor Freight scanner could detect? Also, what is the brand/model # of that scanner? The cheapest Harbor Freight scanner I could see on their site was one for $75.

esl_97_850_T5