97 850 GLT - the O2 sensor connector (Rear) got caught in the u-joint of the steering solumn when I was turning and ripped the wires out of the connector, I pulled over and shut off the ignition when moving the O2 sensor wires, one of the live wire touched the body of the car and it glowed momentarily (3 sec) before I pulled it away. Now the car does not start. I will be replacing the connector and both O2 sensor. The car had no problem prior to this incident - Could it be the ECM??

I am planning to send the ECM to ATE (www.autoecu.com) in West Palm Beach, Florida to check it out and rebuild if required, anyone used the services of ATE or know of a good Company that rebuilds ECM.

Thanks
mz1214u

 

Did you make sure none of the fuses Blew?

 

Yes, that is the first thing I did checked all the fuses and found no blown fuse.

mz1214u

 

Check the other plugs just above it and make sure it didn't also break the engine speed sensor plug.

 

Firstly, I am making the assumption that with the rear HO2S disconnected, I can start the car although it may run rough.

I checked all the fuses, then I checked all the connections around the HO2S and all mechanical connections looks good on physical examination, I did not do any electrical measurement. I just received new HO2S both front and rear and I will be replacing them, if it still fails to start I will attempt to find error codes using OBD II.

The schematic shows that the HO2S goes directly to the ECU, in the ECU the front HO2S (green wire) connects to the Mass Airflow Sensor Circuit and the rear HO2S (green wire) connects directly to the EGR Circuit.

Do you know of a good company that rebuilds ECU, I looked up ATE ("Auto and Truck Electronics") URL: www.autoecu.com I am planning on having them checkout my ECU if my car still fails to start.

In the black housing there are two electronic boards one is a Bosch P/N 0261 203 936 I would guess that this is the ECU. The other board is 12V Aisin AW Co. Ltd. Japan What board is this??

Thanks
mz1214u

 

I don't think the O2 being unplugged will stop it from running either.

But still install them and go from there.

I hear that the company ECU is pretty good.But haven't heard from that many people.

The other control module in there is the transmission control module.

 

Replaced the HO2S, but I am a little confused.

The front HO2S that I removed was Bosch P/N 0258 005 063 and the replacement HO2S was Bosch P/N 0258 005 097

The rear HO2S that I removed was Bosch P/N 0258 003 593 and the replacement HO2S was Bosch P/N 0258 005 062

The new replacement HO2S had cable that was almost 3 feet longer, This is because some HO2S is after the catalytic convertor whereas my Volvo rear HO2S is at the catalytic convertor only 6 inches behind the front HO2S, I had to coil all that extra 3 feet and of course as you know there is not much room in that area.

Another thing, when I finished the installation and hooked up the battery I had the emergency light flashing and you couldn't do a thing. I disconnected the battery a few times and that problem went away but the car still won't start. I will try and read for error code and I am guessing that the ECU is NFG (Not Functioning Generally)

Thanks for your help and your input

mz1214u

 

Dear Tech

Now I am really stuck.

Replaced both HO2S and tried a new ECU from a Volvo wrecker that assured me that the ECU was from a running Volvo and I saw the car myself. Car still does not start.

What else can I check.

Thanks
mz1214u

 

Start back at the basic's
Check for fuel and spark and see if you are missing one.
Also try to check for injector pulse from the injector wiring.That is to be checked while the car is being cranked.

 

You might want to check out this link. Apparently 1997 models need an additional harness.

http://www.fcpgroton.com/volvo850oxygensensors.htm

 

Thanks, I read that notice and all it does is add an extension it may make sense maybe with the front sensor but with Bosch 15062 sensor for the rear it make absolutely no sense to add an additional one feet when you already have an extra 3 feet of wire that you have to coil up and store in a space where there is no spare room.

I went right to basic and checked out the fuel as you suggested, the fuel pump is not receiving the 12V (no sound that is associated with fuel pump) when key is turned on or when engine is cranking trying to start. The fuel pump relay has 4 pins (Nos. 15, 31, 87, 31b) Pin 15 has 11.8V when ignition is turned on and Pin 31b has approx. 4V no voltage on the other pins the reading is the same when the key is turned to crank to start the engine. I cannot determine which pins are for the primary coil and which pins are for the secondary (switched) to supply 12V for the fuel pump, rudimentary line schematics shows that the primary coil is connected to the ECU.

Next step I am contemplating is to momentary provide 12V to the fuel pump and see if the engine start before I do that I need to establish which wire goes directly to the fuel pump either at the relay (which Pin ???) or at the connector just above the fuel pump, this connector has 4 wires two black and 2 pinks (don't know which black and pink wire goes to the pump - according to European wiring convention black will be ground and the pink 12V) probably will pull the fuel pump out to find out which set of b/pnk wire goes directly to the fuel pump. If I can find a relay I might change the relay prior to doing all of the above in hope.

Any suggestions or comments before I undertake the above task???

Thanks
mz1214u

 

This is a pretty good site with wiring diagrams. Might help you out:

https://www.volvotechinfo.com/wd123/

 

There should be a red and black wire that feeds the fuel pump. Some also have a black wire with a small white round plug that comes off a wire on the plug that feeds the pump.To help you find the right plug.

 

Thanks, the wiring diagram is exactly what I was looking for. I now have several option to try out to find my problem.

mz1214u

 

Car won't start - but getting closer. The problem is in the Fuel delivery system. The injectors solenoids are not turning "ON" to allow the fuel into the engine. This make sense as the HO2S (green wire) wire are directly connected to the wires for all the injectors wire at Branching Point 23/11. Do you know if this Grn wire is live all the time?? Any suggestion whatelse I can check out??

Thanks for the link to the wiring diagram, without it I wouldn't have reached this far.

Thanks
mz1214u

 

I'm glad the wiring diagrams have helped you out! I am *way* over my head on this one but did you wind up replacing the relay as you mentioned in your earlier post?

 

The wire should have power. The ECM pulses the ground part of the circuit to make the injectors fire.