Deleting the Secondary Air Pump
 

i have just come into possession of a 1996 2.0l 850 with an air pump. I was intending to use it as a donor car, for my 2.5 850 & my 850 T5. But being soft of head & heart, I think I may try and get it back on the road. It has 2-rotten front wings & a gouge that covers both nearside doors & the rear near side wing. However, it has a long and extensive service record and runs sweetly. It is showing an EML which when the code is read points to a faulty Air Pump. It has been replaced before, but they do not seem to last long. I have seen a Robert DIY mod whereby you can delete the pump by soldering a diode from points 32 to 37 in the ECU, or between 2-wires in the harness under the ECU.. Has anybody carried this out successfully and if so can you advise which diode I should get from RS please.

Deleting Secondary Air System (Air Pump)
 

I have followed a tutorial on Mathews Volvo forum and soldered a diode between the 32 & 37 positions in the ECU. However, after a few seconds from starting the engine the EML light still comes on. I ran the codes and it is showing up as 4-4-2, which means that the air pump is still faulty. So I cleared the codes and got 1-1-1, which was fine. After starting the engine again after a few seconds the EML light came back on & the code 4-4-2 reappeared. Do I need to disconnect the air pump as well to stop the ECU thinking it is still malfunctioning. If so is that the only disconnection I need to make pleasse. Any advice welcomed.

Out of interest what does the secondary air pump do?.Is it on all petrols or only certain flavours?

Deleting SAS (Air Pump)
 

I dont know if it has been supplied on all cars, but the one I have is on a 2.0 litre 1996 850 10 Valve NA. They are not common on cars for the UK market, as they were designed for easier starting in colder countries & the US where they are mandatory in some states for emission controls.. I guess they are useful on the less than 1% of winter days in the south, that are below zero. I dont know why this car has it, but they are a very poor design, being mounted at the bottom of the car under the battery tray, susceptible to water & road dirt. They corrode badly & get filled with water then short out. A lot of people just delete them from the ECU by soldering in a diode between 2-of the terminals, which bypasses the control & makes the ECU think its still there, so no EML. I have done this but the EML still comes on & when reading the codes 4-4-2 shows up, which cites the Air Pump as being the fault. I have cleared the codes, but it comes back again. I am going to try unplugging the SAS to see if that cures it. Nobody else seems to have carried out this mod, so I am in the dark.

Deleting Secondary Air Pump System
 

Re my recent post about this, I am really surprised that nobody has done this. I know that the Air Pump is probably not a common fitting on UK cars, but I have read that they ofetn go wrong & they cost a fortune to replace. Deleting the pump from the system is the favoured method to overcome the problem. I have done this by soldering a diode into the ECU that make it thing the AP is still operational. However, I cannot get the EML to go out & the code still reads 4-4-2. Has anybody any experience or advice to give please?