Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
GPS Input Signal
On vehicle equipped with a GPS receiver, (Mk-I and II) the information from the receiver is transferred to and from the Navigation computer via a 4 wire bi-directional interface. The navigation computer will send a "request" to the GPS receiver for the current vehicle position. This request is sent over a two wire link. The two wires are referred to as RXD and RXDN.
The navigation computer receives the current vehicle position over another 2 wire link referred to as TXD and TXDN. Each two wire link is similar to the CAN line but is unidirectional. When a "data burst" is transmitted, it is mirrored on the other wire as a self-check of data transmission.
Do not confuse these signals with the diagnosis bus (TXD/RXD), the are only related in name, not in function.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.