Playing with the OBD-ii... got the mileage?

[thecheat]

Hi, I'm trying to make this work on my 96 850 turbo but it isn't happening... I only had a 1.5k resistor on hand with my red led, is that maybe my problem?

I put my socket in the obd port with the key off and the led is dim, when i turn it to II the led goes out and it is either off or full bright with the button held. When i click it 5 times, nothing happens.

I read all the codes except the engine computer and cleared them all except the ecu. Do I need to clear these first?

Edit: my battery migtt not have enough voltage to do codes from the obd plug. I did read codes into vol-fcr though. When tryingmto access some systems, vol-fcr says to do the same circuit except with pin 3 instead of 7. Will try this later.

turns out the seller wasn't kidding about the battery needing to be replaced. I got three good starts out of it then dead as a doornail. And of course the 4 month old battery from my e32 BMW is 2" too wide.

[jfukuro]

I have a '96 850 and I tried to read the odometer value with no luck.

The socket under the coin holder is labeled OBD-II. I used pin 16 for power, pin 5 for ground and pin 7 for data. Just plugging in the code reader caused the led to come on (with the ignition off and also in the accessory position). When I pushed the switch, it caused the led to become brighter. Pushing the switch 5 times gives no response.

My multimeter shows 12V DC from pin 16 to pin 5 - but also from pin 16 to pin 7. Is this right?

Any help appreciated!

[jfukuro]

A quick addition: I used a 430ohm resistor with a standard white led from Frys, and a momentary spst pushbutton switch.

[takane2]

Did you try it with ignition on? I am pretty sure it needs to be in the 'on' position.

[thecheat]

I can't make it work on my 96 either... I sort of just gave up on getting the miles since I replaced the timing belt anyway. I can read climate control, engine, and another system just fine.

I can't do diagnostics like mix motor limit calibrations in the ECC system while I can read the codes. It might be certain engine management systems can do it and others can't. I sure would like to just get an older ECU and graft the fly wires in to the engine compartment. What a stupid thing to eliminate such a useful diagnostic tool.

[takane2]

How are you reading the engine codes? I couldn't figure out how to make it talk to anything but the instrument cluster from that pin. Using another one i was able to read cruise control stuff I think.

[thecheat]

I think it's #3 that talks to the ECU. Press the button for half a second and it starts talking. I will have to check what my tool is later but I think the possibiltiies are #3, #7, #8 (??) and #13 (??) ECU, instruments, ECC, and something else... don't quote me on those, i"ll check later.

[takane2]

Some one asked me to post some a picture of the circuit.
Here it is:

IMG_20120806_175014.jpg (76.41 KiB) Viewed 2031 times

As you can see the yellow wire is connected to the resistor. It goes into pin 16. The resistor is connected to the longer LED lead(positive). The shorter(negitive) lead is connect to the other side of the breadboard and the ground and data wires connect to it. Put the green wire into pin 5 and the red wire in pin 7. Disconnect and reconnect the wire for pin 5 at the breadboard, it is easier. Or if you want to be fancy you can use a SPST switch. But you really don't need it. I don't have the car anymore so I can't show it hooked up. The OBDII port is under the coin holder(it is actually a cover) in front of the gear selector.

[schmuecker]

I have built this today - looks very similar to your picture - i also included a SPST switch though (always open one). I tried testing it on my '98 V70 but it didn't work. none of the trouble codes are being indicated. Basically I get a red light each time I press the button (lets say one time a long second to read out), but then nothing happens. So the LED is working. I also just connected the pin 5 and 16 to the LED & resistor and it lit up.

Not sure if I'm doing something wrong or whether this actually DOESNt work on the '98 V/S70 (althought someone suggested that it should). So if anyone has tried this on their later model year car, can you confirm it does indeed work?

I'd like to use this on a 850 that I am shopping for to replace my V70 (have burnt valves and dont warrant repair of engine). So ideally I want to test this before I am in a seller's car with broken odo. So if someone in the Bay Area has a 850 and don't mind meeting up, I'd love to test it out. I'm even thinking of making this into something more premanent like soldering the led, switch and resitor into a OBDii extention cable that I found, so that I'm not sitting in someone's car with a breadboard...

Cheers.

[erikv11]

Conventional wisdom on the forums is that only the Volvo scan tool can get mileage from a 96+ 850, and even that is tricky and many dealerships don't know how to do it (jimmy57 posted it up here).

I have no doubt this will read codes, have seen that posted many times, but it would be very interesting to know if this works for getting cluster mileage on a car other than takane's. Someone please meet schmuecker so he can try it!