Using an OBD2 jumper can be a handy trick for accessing diagnostic codes on your vehicle, especially when dealing with issues like a blinking transmission indicator. Many DIYers turn to online forums for guidance, like the Honda Element owner who encountered a flashing “D” light. Following forum advice (Flashing “D” light – how to solve and D light is blinking for no apparent reason NO CODES), the user attempted to use a jumper on their 2008 Honda Element with 78,000 miles. However, a simple mistake led to unexpected electrical problems, highlighting the importance of precision when working with your car’s OBD2 port.
The intention was to jump pins 4 and 9 on the OBD2 port to read the transmission codes. Unfortunately, due to an inverted perspective while looking at the port, the user inadvertently jumpered pins 5 and 16. This error resulted in a short circuit, connecting pin 16, which provides +12V battery power, to pin 5, the signal ground. Referencing a common OBD2 pinout guide confirms this misstep connected power directly to ground, a situation that can lead to electrical issues.
Here’s a reminder of the correct OBD2 jumper placement, crucial for avoiding similar mistakes:
Correct OBD2 Jumper Pin Placement for Diagnostics
Initially, the user didn’t realize the error. After correcting the jumper to the intended pins 4 and 9, they successfully retrieved a transmission code (26, indicating a faulty 3rd clutch oil pressure switch). However, the relief was short-lived. Upon starting the vehicle, a range of electrical accessories were no longer functioning. This discovery strongly suggests that the brief short circuit in the OBD2 port caused by the incorrect jumper placement was the culprit.
Despite checking fuses, the following systems remain non-operational:
- Radio
- Dome light (only works with key in the ON position)
- Power locks:
- With the key ON: Unlock button works, lock button is non-responsive. Manually pushing the lock knob on the door locks all doors.
- With the key OFF: Lock buttons are completely inactive, manual lock knob has no effect on other locks.
- Remote key fob: No functions working.
- Cruise control enable button: No illumination when pressed.
- OBD2 port: No power (12V) at pin 16, rendering diagnostic scanners unusable.
Interestingly, the symptoms bear a resemblance to a reported issue in a 2004 Honda Element with radio power loss, although that case lacked a documented resolution.
This experience serves as a cautionary tale for anyone using an OBD2 jumper for diagnostics. While it can be a useful technique, precision is paramount. Shorting pin 16 (+12V) to ground within the OBD2 port can lead to a cascade of electrical problems. If you encounter similar issues after using an OBD2 jumper, especially after a potential misconnection, it’s crucial to systematically check fuses and potentially consult wiring diagrams to pinpoint the source of the electrical malfunction. Further investigation is needed to determine the specific fuse or component affected by this OBD2 port short circuit in this Honda Element.
