How to use the On-Board Diagnostic (OBD) unit.

Kirby J · Post by **Kirby J** » 25 Apr 2010, 19:10

I finally found the plug you were describing. On my REX/REGINA 940 there are two separate boxes just in front of the left strut mount. I have pulled a few codes on the first section of the note, and will slowly work my way through them. I never knew the 93's had any kind of OBD. Thanks again for your notes on this.

Kirby J
Now up to 356K miles and counting.

mcbride · Post by **mcbride** » 21 May 2010, 21:51

1991 240 Ignition system fault codes Cable in #6 obd socket. Pushed button 2 times and code seemed to be a constant flash. Not any countable flashes . Thanks for any help

Post by **billofdurham** » 23 May 2010, 11:01

Pushing the button twice takes you into diagnostic mode #2. Was this what you wanted or was the second push a mistake?

Bill.

Marsha · Post by **Marsha** » 23 May 2010, 16:18

Hello, I am first time user, also not a mechanic, - I have a 850 '94 non-turbo wagon (Sonya , the red we call her) anyway, she has been ailling lately - she went from not wanting to warm start to stalling while driving down the road (scary) - then when you get to where you wanted to go and she has sat for a couple hours - she still doesn't want to start. I ran the diagnostic codes and have attempted to read your advice blog - but now I am at a loss and terrified of the cost to fix. I live on SSI-Disability - anyway - my codes are (A-2) 111 (A-6) 314, 324 and (A-7)122 and 231 and the ABS idiot lite has always been on since I bought her, and they said they never tracked down that problem - anyway, back to current problem - I thought it was the fuel-relay #103, and I went to Radio shack and bought the capicators to replace, before running the diagnostic check - and the relay is still screaming (buzzing). So is it the fuel-relay or the CPS or the Ventilator damper motor position sensor or time to call a mechanic and be without a car?

mcbride · Post by **mcbride** » 23 May 2010, 19:37

billofdurham wrote:Pushing the button twice takes you into diagnostic mode #2. Was this what you wanted or was the second push a mistake?

Bill.

I didn't know what would happen with the second push. I thought the quick flashes where codes. I thick I figured it out and the only code coming up is 113 which I believe is fuel injector related. I had previously unplugged the o2 sensor wire. Could that have caused the 113 code? This car has had fuel problems . The injectors where replaced, new fuel filter,plugs , plug wires, and who knows how much starter fluid the previous owner had dumped into it. I had had a lot of trouble starting it cold and hot. Yesterday I replaced the fuel pressure regulator and it starts great now. But I think it could use a new o2 sensor? Thanks

Post by **billofdurham** » 24 May 2010, 15:41

I didn't know what would happen with the second push.

Now you do know. Sometimes the best way to find out what something does is to try it.

1-1-3 can be either injectors or fuel pressure. You have now covered both so should be good. Erase the code if you haven't already done so as the car will still think there is a problem.

Unplugging the oxygen sensor shouldn't have thrown that code but occasionally one comes out of left field to cause total confusion.

Bill.

Post by **billofdurham** » 24 May 2010, 16:16

Marsha, welcome to Matthew's Volvo Site.

The OBD on the 850 is more complex than on the older rear wheel drive cars.
A2 1-1-1 means no fault was detected on the fuel system.
A6 3-1-4 and 3-2-4 are both related to the camshaft position sensor. 3-1-4 is camshaft position sensor signal absent and 3-2-4 is camshaft position sensor signal absent intermittently. The attachment shows the location of the camshaft position sensor. Check the wiring to see that the insulation isn't worn and check the wiring connector for good fit. Take the connector apart and check there is no oxidation on the pins.

850 engine sensors.pdf: (157.66 KiB) Downloaded 480 times

A7 checks the instrument panel.
1-2-2 is temperature signal interval too long. Does your temperature gauge stick at minimum?
2-3-1 is not listed for A7 so you have probably misread the code.

Before committing to taking Sonya to a mechanic erase the codes and drive her to see if they return. Sometimes this does work.

Bill.

dedrums · Post by **dedrums** » 02 Feb 2011, 15:37

i have a 1992 740 station wagon regina ignition and i cant find this darn thing you sure its there thanks alot

dee23 · Post by **dee23** » 04 Feb 2011, 12:36

i cant download the instuctions for my 740 so i dont know how to use or read the OBD. the codes do me no good if i dont know how to find them. Can someone please help. My wife and I are STRANDED without this car. Just let me know where to look and what to do to get the codes for my 1991 740 gl non-turbo wagon. Ive just replaced the cold start injector valve ($259.00) and dont know if thats the prob. because I cant start it or find the codes. Cant afford a mechanic, I greatly need and appreciate some assistance here. Thank you

Whitebrick · Post by **Whitebrick** » 05 Feb 2011, 09:24

It says where it is in the first post, by the strut/wheel well in the engine compartment. It's a little black box with a lid that pops off.

How to use the On-Board Diagnostic (OBD) unit.

Re: How to use the On-Board Diagnostic (OBD) unit.