1996 850 T5 ECU conundrum - OBD2 only talking to tranny

Sommerfeldt · Post by **Sommerfeldt** » 19 Apr 2015, 12:05

Right - I've tried searching this and various forums for a solution, but with no real luck. So apologies if I missed something - I really tried!

Anyway, here's the problem.

I have a 1996 850 T5, rolled about 229k km, which I bought for relatively cheap. Some paint issues, some control arm issues, and other small stuff, but nothing major. Previous 2 owners were both Volvo dealer employees, so service records seem spotless. Changed hoses (air and most vacuum), but that's as far as I've come.

I've had an intermittent CEL (lambda-light, as I've always called it) since I started the thing w/o plugging in the MAF when changing the air filter to a K/N drop-in, and that has now become a permanent thing. It doesn't worry me too much - car runs fine, doesn't use more gas than I expect, pressures are good and all of that. Still, I'd like to know what the car thinks the problem is. I expect a MAF issue.

Anyhoo - I've got an ELM327 WiFi dongle (/adapter/whatever) which doesn't seem to be able to talk to the car. I've tried the main apps out there - DashCommand, Shift, EOBD Facile - and this occurs on all of them.

All the apps connect to the WiFi thingy, so there's power. All the apps seem to search through the modes, and then no data except battery voltage shows up. In one of the apps (I think it's EOBD Facile), it asks me to select ECU, and then only shows tranny ecu. So, my question (finally) is how do I make the engine ECU talk to me, and/or what could be the problem that makes the tranny talk, but not the engine?

I don't have the diag boxes in the engine compartment (looked for them, since I was used to using them on my old T5-R), and I'm not familiar with electronics to make my own blinky thing. Also, I'd love to have the ability to read the (semi-)live data the OBD2 port can feed to these apps.

Anyone?

Post by **misha** » 19 Apr 2015, 13:30

Did you checked fuses in fuse box?There are few of them for diagnostics.

Sommerfeldt · Post by **Sommerfeldt** » 19 Apr 2015, 13:39

Yep - all fuses are good to go - I did that first when I thought there was no power on the socket, and I hadn't pushed the adapter in well enough...

- S

Sommerfeldt · Post by **Sommerfeldt** » 21 Apr 2015, 07:04

I'm allowing myself a single bump on this one.

No one has any suggestions?

- S

Post by **Ozark Lee** » 21 Apr 2015, 07:20

The ELM 327 can't really talk to a Motronic 4.3 ECU. There is more information at this link as well as some software and terminal commands to talk to other stuff in the car like the instrument cluster, the seats, ABS, and SRS. As you noted, it will talk to the transmission TCU as well.

http://jonesrh.info/volvo850/index.html

...Lee

Sommerfeldt · Post by **Sommerfeldt** » 22 Apr 2015, 07:01

Hm... well, I don't need them to have long discussions - simply listing codes and clearing them. I may be reading this all upside down, but it seems the ELM should be able to do that?

From your link:
"All of the car's ECUs (that I know of) can communicate with the ELM327 in a useful manner.

For instance, all of those ECUs can have their non-emissions diagnostics DTCs both read and cleared with an ELM327 -- at least with the two ELM327 compatible devices that I have used. For my 1997 Volvo 850 T5, the DTC reading/clearing also includes the KWPD3B0-conversant ECUs: ABS, SRS, COMBI Instrument Panel, AW 50-42 Automatic Transmission, Power Seat Left, and Power Seat Right. I suspect this would also include the Immobilizer ECU for those cars that have it."

- S

Post by **Ozark Lee** » 22 Apr 2015, 14:10

Your '97 likely has a Motronic 4.4 ECU. The Motronic 4.3's are trouble for many of the code readers including the VAG-COM. From that same link, and I will defer to them since I haven't tried it:

The Motronic 4.3 ECU can be communicated with via the OBDII port 3 using a flashing LED tool. And it can be directly addressed via a VAG/COM KKL cable if the pin in the VAG/COM KKL cable destined for OBDII port 7 is switched to go to OBDII port 3 instead. But the Motronic 4.3 ECU can not be directly addressed by the ELM327 using "physical addressing" (even if ports are switched), simply because the Motronic 4.3 does not communicate via the OBDII port's pin 3 using a ISO9141-2 like protocol which the ELM327 can understand.

For reading codes on my '96s I have always just used a really cheap (Harbor Freight Version) Autel MS309. It doesn't do much (no live data) but it does read and clear codes on the Motronic 4.3 cars and I think it was around $30.00 US and they are even cheaper now.

...Lee

Post by **misha** » 22 Apr 2015, 15:54

Ozark Lee wrote:Your '97 likely has a Motronic 4.4 ECU...

Nope.T5 from '96 is still Motronic 4.3.

Non turbos in '96 can be Motronic 4.4 & Motronic 4.3 but ALL '97 non turbos are Motronic 4.4.
Turbo cars up to '98 are all Motronic 4.3...even some of them in '98 are 4.3.

Post by **esl_97_850_T5** » 22 Apr 2015, 16:11

Sommerfeldt,

There seems to be some confusion between the title of this thread and your "Current plaything: '98 S70 T5..." signature.

Answering the following questions can probably help us guide you to read/clear whatever codes are causing your lambda light to come on.

Do you have a 1996?
Do you have an 850?
Do you have a T5?
Is it manufactured to be sold in Norway?
Does it have a Motronic 4.3? Or Motronic 4.4? Or some other engine/fuel ECU?
Does the M43, M44, or whatever have factory software?
Or has it been flashed with an ARD tune or some other special tune?
Or has it been flashed with the USA software (that allows OBDII emission diagnostics communication with both transmission and engine ECUs)?

If your M43, M44, or whatever engine/fuel ECU does not have a complete set of the OBDII emission diagnostics software then you might encounter:

- absolutely no response when trying to talk with the software packages you mentioned, or
- communicating only with the transmission ECU (but only having it report that it includes a single PID, namely PID 0100) and not communicating with the engine ECU [this appears to be your case], or
- communicating with the engine ECU (but only having it report that it includes a single PID, namely PID 0100).

With all 3 of those types of responses or lack thereof, you can basically conclude you don't have useful OBDII emission diagnostics. What that means is your ELM327 will not do anything useful with the standard OBDII emission diagnostics oriented software packages.

However, you can still read/clear DTC codes of the Motronic 4.3 and Motronic 4.4. But it has to be done with a protocol which is not the standard OBDII emission diagnostics protocol.

To repeat: Answer the questions, then we might be able to explain the possible ways to read/clear the codes of your particular engine ECU.

esl_97_850_T5

Sommerfeldt · Post by **Sommerfeldt** » 27 Apr 2015, 05:49

Hi esl_850_T5!
And thanks for all the replies. Sorry about the confusion - I'll fix my sig.

The issue is a 1996 Volvo 850 T5.
It was manufactured in Sweden, for sale in Scandinavia - imported directly from Sweden to the Norwegian market.
I believe it to be an M43. Nothing has been done to the ECU(s), so it stands to reason that it's an M43.
Factory software. Nothing has been changed on this car.
No flashing, no special tune.
No flashing with USA software.

- communicating only with transmission ECU (inc. single PID 0100), no communication with engine ECU is correct. My issue.

esl_97_850_T5, you say that I can still read/clear DTC codes from the M43 and M44, but with a different protocol? I may be a slowpoke, but I thought that the ISO 1430-4 KWP (5 baud init, 10.4 kbaud) was the right one?

Again, thanks for anwering - I think I covered the questions, yes?

- S