Auto Service Professional

JUN 2018

Magazine for the auto service professional

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52 A S P J u n e 2 018 gain access to the FES sensors, and the first step should be to unplug the sensor in question and inspect for corrosion. If corrosion is found, that sensor will need to be replaced along with possibly the pigtail. ese FES sensors are prone to water intrusion and don't need to be calibrated aer installa- tion. Simply use the scanner to erase the codes. If no corrosion is evident, swapping the sen- sors side-to-side is an easy and quick way to diagnose a failed sensor, especially if the code is B0084-39 (internal sensor failure). e code should move to the other side and maintain the same suffix (remember to mark the sensors L/R so you know which is which). If the code doesn't move, you are going to have to inspect the wiring and the SRS module and follow the appropriate diagnostics using the sub code as well in the service information. Another common GM pickup SRS failure involves the side impact sensor located inside the le front door. ese side impact crash sen- sors work by sensing the air pressure change during a collision as the door is crushed. If the code retrieved is a B0085-00 le front side im- pact sensor high circuit, look first at the wiring harness in the driver's door jamb at the A-pil- lar. If the truck is used by a contractor or deliv- ery service and the driver's door is constantly being used, the wires that go to the crash sensor in the door have likely broken. 2001 to 2006 Honda Civics have a common failure in the seat belt buckle switch. ere is a small three-wire switch that is located inside the female part of the seat belt that tends to fail. Because the SRS system needs to know if the occupants of the vehicle are wearing a seat belt, a switch failure will trigger the SRS light and typically set an SRS DTC 9-3: faulty driver's seat belt buckle switch. Inspection for this code involves a voltme- ter to check for voltages at the seat belt harness connector while it is still connected. Verifying that the buckle switch has a good ground is the first step. Back probing on the seat belt side of the connector is next. Key-on voltages should be: • Black wire should always be a good ground. • Voltage with seat belt buckled: red/blue wire = 5-12V, blue/red wire = 0V. • Voltage with seat belt unbuckled: red/blue wire = 0V, and the blue/red wire = 4.5 to 5V. If these voltages aren't found, unplug the connector and check for voltages on the harness side. e SRS module will need to see both cir- cuits open or grounded at the same time to set the 9-3 code. e ground G551 for this switch is located underneath the front passenger seat, and can become corroded from water intrusion due to flooding or salt-laden winter boots. ese Honda Civics require a scan tool to retrieve the SRS codes and a scanner is recom- mended to erase the codes but isn't required. You can use the yellow plastic memory erase signal (MES) connector, located in the fuse box and the special Honda SCS 07PAZ-0010100 tool (I have used a jumper I made from a used harness connecter aer I removed the locking tang) and follow this procedure to erase the codes. I've had to do this procedure more than once to get the codes to erase. is procedure can save time as compared to using a scanner if you already know the SRS system has been repaired, say at a body shop. 1. Key off. 2. Connect the SCS tool to the NES connector. 3. Key on. 4. SRS indicator light on for about six seconds, then goes off. Remove the SCS tool within four seconds of SRS light going off. 5. SRS light on again, reconnect the SCS tool within four seconds. 6. SRS light off again, unplug the SCS tool within four seconds. 7. If the SRS light should blinks twice indicat- ing the code/codes are cleared 8. Key off wait 10 seconds, key on, SRS light should come on for about six seconds and go out. It's also important to note that Honda does not want you to repair the SRS wiring harnesses. According to their service information, if there is corrosion, the entire harness is supposed to be replaced. Common SRS output issues Many output issues can also be diagnosed with a non-factory scanner to retrieve and clear S R S D i a g n o s t i c s

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