I put a power seat on my pass. side.ran pos. and neg. wires from driver seat,now service airbag message is on

If you are experiencing unresponsive driver side power seat controls and an SRS (Supplemental Restraint System) airbag warning message on your 2008 Volvo S40 2.4i, it could be caused by a few different issues, such as:

1. Faulty seat control module: The seat control module is responsible for controlling the power seat functions. If it is faulty, the seat controls may not work and the airbag warning message may appear.
2. Wiring issue: A damaged or corroded wire connection can cause the seat controls to become unresponsive and the airbag warning message to appear.
3. Sensors issue: The seat and airbag system rely on a variety of sensors to function properly. If any of these sensors are malfunctioning, it can cause the seat controls to become unresponsive and the airbag warning message to appear.
4. Airbag module: The airbag module is responsible for controlling the airbags in the vehicle. If it is faulty, the airbag warning message will appear.

It's best to have a professional technician diagnose the problem and recommend the appropriate course of action. Sometimes, the problem can be solved by replacing a faulty module, repairing or replacing damaged wiring or sensors, but in some cases the repair may be more complex.
It's important to note that the airbag warning light should be taken seriously and repaired as soon as possible, as it can indicate a problem with the airbag system that could affect the safety of the vehicle in case of a collision.

A fuse blows because the circuit it provide power to has a shorted component or wire.

Most the problems it is seat.check wires.

There are two junction connections on the four wire harness that runs from the SDM (airbag controller under driver seat) to the passenger side airbag (I/P module). Once connection is just below the passenger side airbag in the dash and another is behind the driver side kick panel.

In my case, the connector behind the driver side kick panel had likely a bit of corrosion and there was high resistance that thre the service airbag message and light on the dash. Once I cleaned this connection, the light was gone and the problem is now fixed.

High resistance in either of these connections will throw the B0019 OD code.

If they pulled the dash then possible they removed the seats and stretched the wires or left them disconnected
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DISCONNECT THE NEG BATT CABLE FOR 5 TO 10 MIN. FIND PASS AIRBAG FUSE AND PULL IT OUT. AIRBAG IS BEHIND THE PASS TRIM PANEL. DISCONNECT WIRES BEFORE REMOVING AIRBAG. TAKE CARE NOT TO SET OFF AIRBAG. DO NOT PULL OR CARRY BY WIRES OR EDGES OF THE DEPLOYMENT DOORS!!

depending on which one it is, pass or driver seat, its within the female reciever of seatbelt. easier to remove seat and inspect wiring to pretentioner. check for open by unplugging it and check across connector w olhm meter. if no reading, its open and needs replacd. unhook your battery before attempting this.

Probably for some sensor located in car seat telling computer that someone is seated there and possibly activating air bag circuit. Those bags are expensive and you do not want opening when not necessary.

Do you have anything under the drivers seat? Fords will put the airbag module under the seat, if anything is packed around it, it can cause the airbag light to come on. Remove any items around it and check the connectors are firmly in place.

the switch should only have a pos or neg not both the most common is a pos set up, the light cluster will be earth to the body and the live will go to one side of the switch and when the switch is pressed travel from the other side down to the light cluster and the bulb will light up try this set up all so re check the loom as it sounds like it may be earthing some where from switch to light