OBD2 on early 850s

[ShadeTek]

Hi, I've been searching around trying to find why my UK RHD OCT 1995 855 2.5 CD cannot be scanned with 3 different OBD2 scanners I have. It seems that the OBD2 socket is connected to the dashboard as I can reset the service light via the OBD socket with an SIR-V tool, but it may not be connected to the ECU by way of the K-line. Can anyone shine a light on this? Any Volvo electricians out there who can give me more info on this? Is the ECU OBD compliant or just not connected?

Man thx

Tek.

[cootuk]

As far as I know, the last 850s had the code reader moved from inside the engine bay and the wires plugged into the OBDII socket (I think this was for the US regulations), but the socket isn't OBDII compliant at this point.
The codes on my 2.5l 10v Fenix can be read from the OBDII socket using a simple circuit of a switch, led, and resistor....in a similar fashion to how the codes were read in the engine bay.
Someone off this board emailed me the details in about Jan 2002.
I might be able to find the circuit diagram somewhere....don't know which exact models it covers though

[Chris_Rogers]

Heres's the info from the somebody.

You can read/reset the codes on this model yourself if
you're willing to make up the following circuit.

On '96/'97 850 cars with the 16 way 'OBDII' socket, and
maybe other models, some of the control modules use 'flash'
codes.
To retrieve the flash codes the following procedure can be
adopted:
Connect an LED, with the correct polarity, in series with a
1k8 ohm resistor, between pin 16 (+) and pin X, where X is
the pin corresponding with the module to be read. Connect a
push to make switch between pin X and pins 4 or 5 (-).
The circuit can then be used in the same way as the pre '96
diagnostic sockets, situated in the engine compartment.

For:

Motronic 4.3 or Fenix 5.2, X = 3.

850 ECC , X = 6,

Timer Type 4, X = 9.

All models: Cruise Control, X = 13,

900 & S/V 90 ABS, X = 12 .


The only 850 engine that's OBDII compliant is the late 20V model with Motronic 4.4.
The auto gearbox on '96 models will respond to OBDII to a very limited extent.

[cootuk]

That's the one....works fine on mine the couple of times I've had to use it though the LED appears to flash painfully slowly when you're actually reading the codes.
Electronics stores like Maplin stock the parts, except for an OBDII connector last time I looked, so I used an automotive crimp connector to push into the socket with the ignition turned off.

[ShadeTek]

Hi, yes that seems to all add up now. I have 8 wires on the rear of the socket. They must connect to various ECUs in the car. I will build an interface and try them out very soon.

Pin Function
16 -+12VDC
4+5 -Earth
12 -abs
3 -Fenix 5.2
6 -ECC
9 -timer
13 -CC

THX

Tek.

[Chris_Rogers]

It may work out like that, but I doubt you have a timer type 4 it's for the additional heater that prewarms the car in very cold climates.

I would take a note of the colours of the wiring on the socket.

If you have a Haynes 850 manual you will probably find the wire colours of the daignostic lines from each ECU will match the wiring diagram for the older A & B sockets.

[ShadeTek]

OK, I've built a small diagnostics unit to read the error codes from the "almost OBD 2" socket in my 855. This is where the pods are wired to the OBD 2 socket in the car.

I can pull codes from:

1.The engine ECU on pin 3. 1-1-1 reported...good news, no faults logged.

2.Climate control on pin 6 has 2 codes: 4-1-7 & 1-4-5 mmmmm

3.Cruise control on pin 13 reads 1-2-2 but I ain't got a look up table for the cruise control. Anyone got one? Nothing in the Haynes manual.

4.No flashes from what should be the ABS on pin 12(if it's the same as the 900's). Anyone know if this isn't the ABS pin? Any info would be appreciated. Also how do I reset the codes? Is it the same as the pod...hold the button in for 5 seconds?

I had a look at the wiring to the pods, they have 8 wires going to them just like the "almost OBD" aka "a OBD2" socket. Colours are different but I guess if they aint reading 0volts then I could pulse them to see if I can pull a code.

I reckon the ABS is on pin 1 or 7. I will find out soon.

THX

Tek.

[ShadeTek]

OK, I can pull 3 lots of codes. One of them is the Climate Control as I get a fault code only specific to that module on the look-up chart. (1-4-7)...on the Haynes Manual. I also get a 1-1-1 code which I am pretty sure is the engine Fenix 5.2. Also, I get a 1-2-2 which I am unsure about. I hope it's the ABS unit as I do get an ABS light on every week or so and pulsing pedal a lot in warmer weather. Fault look-up suggests no RHS sensor siganl below 25MPH, which would tie up as it happens as I slow up a to a stop. Also I reckon pin 7 is the service light reset pin as I have a tool which for this purpose which only has 3 pins on it. Pin 16- 12vdc, Pin 4- 0VDC and pin 7, the reset pin. There is no pin 12 as in the 900's. Below are the pins which are present in the module.

1,3,4,5,6,7,13,16.

I don't know what pin 1 does. I tried to read the codes from it but I got nothing.

[Chris_Rogers]

Pin 1 is for EKZ129 Ignition modules on early 20V cars.

ABS, Immobilizer, Speedo, Power Seat, SRS etc. is on 7.
You will need a Volvo scan tool to read these.

Don't worry about the cruise control code, it's just saying the is no supply, this is normal until you run the car and use the control.

[ShadeTek]

>Pin 1 is for EKZ129 Ignition modules on early 20V cars.

I have a 1995 2.5 10V CD. Would pin 1 still connect to the ignition module?

Thanks.

Tek.