232 replies to this topic

[Yellow95]

Now if someone can figure out a diode to solder in to delete the rear 02 sensor.

Gary

[TravisRay]

_{Wow, read through these posts, and think that I know the answer ( yes it will) but I'd like someone to help me out, I have a 97 960 Wagon with about 180K, has the 6 cyl with the Motronic 4.4. The air pump is between the battery and the engine. I think this mod would work on the car, but can anyone give me a for sure on this? thanks in advance.}

[TravisRay]

I may have posted the wrong information. The car has the Motronic distributorless ignition system — B6304 engine. Sorry for the confucsion. I don't know if the ECM is the same or not, however, I believe the code it is showing for the air pump is the same.

[Fudge_Brownie]

The codes are all part of the OBD-II standard. So they'll be the same usually.
The pump and system are probably the same too, given the same make and similar age.

Here's the catch. This has been tested on the Motronic 4.4 ECU's for 850/X70 cars. So you'd need it to be an identical pin-out on the ECU. That I cannot verify, and while I think very few here can, you'll have to hope someone who knows will reply.

[Volvo5.0]

Fudge_Brownie, on 16 May 2012 - 03:09 PM, said:

The codes are all part of the OBD-II standard. So they'll be the same usually.
The pump and system are probably the same too, given the same make and similar age.

Here's the catch. This has been tested on the Motronic 4.4 ECU's for 850/X70 cars. So you'd need it to be an identical pin-out on the ECU. That I cannot verify, and while I think very few here can, you'll have to hope someone who knows will reply.

Yeah, I only tested it on 850/X70's, but in theory it should work also with 960's and S/V90's. I just looked at the schematic for the 960/SV90, and it looks like the pinouts are the same.

[Fudge_Brownie]

Annnnd one of the few people who could provide some insight is that guy. So, sounds like its worth a try.

[TravisRay]

Outstanding. I'm going to give it a shot. I think I can pull the schematic for the 960, or does anyone know where I can get copy online?

[Volvo5.0]

960 schematic for SAS delete......

[TravisRay]

Thank you very much.

[Eliotg]

Awesome write-up. Thank you for putting it together.

I THINK I was able to eliminate the solenoid control valve and SAS relay entirely using passive components.
For whatever reason you would want to do this, this might be a viable option (but the usual: If you do this and your car catches on fire its not my fault disclaimer applies)

I substituted appropriate resistor values for the solenoid coil (~35ohm) and the SAS relay activation coil (~100ohm) between the correct pins (A37 for control valve and B38 for the relay) and a 12v line switched by the main relay.
I used A27 out of convenience but you could probably use any main relay switched 12v line.

I tested this out on my 98 S70 NA which is a non-SAS car as I had a SAS ecu for the same drivetrain to use.
I installed the SAS ecu and upon startup got two codes 0410 and 0413.
The car did have the plug for the control valve clipped to the radiator fan shroud, so I plugged the 35ohm resistor into it.
Cleared the codes and after startup, just had the 0410 code remaining. I pulled the ECU, soldered in the diode and I still had the 0410 code on startup.
The SAS relay position (#2) doesn't have connectors in it in my car so I added the 100ohm resistor internal to the ECU.

Started it up and no CEL's. It's stayed off and nothing is pending for the past 50 miles or so.
though the SAS readiness monitor still shows incomplete (of course) and I don't have a VTC to test it with.

Maybe I'll try to get the readiness set and see if there's any issues with doing this to get rid of all the SAS components.

[Keaton85]

Nice! that's good to know that the resistor worked. I think I posted that in the past but never actually tried is.

Although my resistance readings on all of the solenoids were 30ohms and not 35ohms. ummm, anyway, I guess I will have to stop by radio shack and pick up a 300% mark up resistor haha.

Wondering if it's best to place the resistor in the harness or inside the ECU solder to the pins just like the diode is?

[Keaton85]

Also, the other issue, is what wattage should these resistors be? REALLY don't want those buggers getting hot...

[Eliotg]

Weird, I guess the one control valve coil I measured had some corrosion or poor solder joints that caused it to meter out at 35 ohms rather than 30.
There's probably a good bit of leeway for actual value. It probably just has to act as a load to cause enough of a voltage drop to that pin from the 12 volt source when its pulled to signal ground within the ecu.

I was thinking along the same lines about where to install the resistors.
If I had the relay wiring in place in the harness, I probably wouldn't have bothered soldering it into the ecu to test it.
Probably would have just soldered pieces of wire onto the resistor leads and spliced into the harness with scotch-locks.
Although, if you put both resistors and the diode inside of the ecu, you should end up with a non-SAS ECU that could be installed in any car with a similar drivetrain.

Its kind of a pain to solder on pin B38 since its on the bottom but not impossible, it just takes some patience.
I used a really long, thin iron and gently bent the pins on either side to get the clearance.

I used 1 watt resistors for both without any problems.

But I should have actually measured what the max current draw was on the actual control valve and done the math to figure out what worse case would be.
By a quick calculation, assuming a drop of 12 volts across the coil, would equal 0.4 amps. So close to 5watts.
Since the ECU sinks the pin to ground, the resistor shouldn't have to dissipate that much power.
It's not doing work like the solenoid coil, unless I'm looking at it wrong.
It's been a while since circuits class.