Electrical - Intermittent Trailer Light Function
TECHNICAL NEWSBulletin Nbr: 03-08-351
Date: August 2003
Market: All
Intermittent trailer lighting
Cars affected
Some Saab 9-3 (9440) M03- with towbar and where the car is used together with a trailer having a 7-pin connector
Background
13-pin connection for trailers is a new standard which provides many advantages for the user, including the possibility to connect the trailer's power consumers to separate connections adapted to higher power consumption and to have both rear fog light and reversing light on the trailer. The Saab 9-3 Sport Sedan (9440) is built in accordance with this standard. A trailer with a 7-pin connection can be connected via an adapter.
When using a trailer with a 7-pin connector connected according to one of the following alternatives
^ all exterior lighting is connected to either pin 5 or 7 in the 7-pin connector
^ extra power consumers (e.g. heating fan) are connected via the trailer's connections for lighting (pin 5 or 7 in the 7-pin connector)
The load becomes too high in the car's REC and in the electronic module for the trailer. This results in the electronics switching on and off which means that the trailer lighting is intermittent.
Symptom description
Trailer lighting is intermittent
Procedure
Alternative 1 (recommended)
Replace the trailer's connector and wiring harness with the 13-pin version. Extra power consumers are then connected to pin 9 or pin 10.
Alternative 2
Make an adapter harness with a 7-pin female contact for connection to the trailer's connector at one end and a 13-pin male contact for connection to the car's connector at the other end. The connectors are connected together as shown.