Troubleshooting Prodigy P2 Brake Controller Installation on 2013 Audi Q7

Question:

Would the emulator be useful in diagnosing a problem? After completing the wiring, I only get full on for brake controller not a corresponding braking to the vehicles braking. All of the lighting functions of the 7 pin to trailer are working correctly. Thanks

asked by: Bob B

Expert Reply:

The Tekonsha 7-Way RV-Style Tester for Brake Controllers # 6562 is intended for troubleshooting a vehicle's brake circuit but I recommend using a multi-meter item like # PT89ZR because this tool will tell you the actual voltage level detected. This makes the multi-meter a more useful tool for general wiring troubleshooting and it costs less too.

It sounds like your trailer brake circuit is the only one on your 7-way setup that is not behaving correctly. The multi-meter will help you determine if there is a problem within the P2 controller # 90885 or if there is a problem in the wiring between the controller and your 7-way. Please keep in mind that this controller will send output power only when you are driving or when you press the manual control. If it always generates full power then it either needs to be adjusted (and your trailer brakes could potentially need this too) or it has an internal fault.

Set your controller to full power and boost and have a helper press the manual override on the unit while you apply the tester's ground and hot probes to the contacts shown in the linked image; ground is at 7:00 and the brake circuit is at 5:00. When your helper engages the manual control you should detect close to or slightly over 12 volts on the circuit.

If you detect substantially less than this voltage you'll want to repeat the test on the blue wire at the back of the controller. Cut the blue wire a few inches from the back of the P2 (leaving enough wire left to re-connect it after the test). If you detect full power on the blue wire but you didn't at the 7-way contact, then you know there is a wiring issue between the controller and the 7-way. If you detect a low voltage right at the back of the P2 when it is set to full power and boost then the controller itself has an internal fault and should be repaired or replaced.

You can also test the trailer's brake circuit all by itself when the trailer and vehicle are NOT connected. This test focuses on the trailer itself, without including the controller or the vehicle wiring in the test. Connect two wires to your battery terminals and then apply them to the appropriate contacts on the trailer's 7-way plug. Please refer to the other photo to see which contacts. This direct full-power battery connection should fully engage the brakes on the trailer. You should be able to hear the brake magnets gently humming and easily feel drag on the wheels. If you do not get this result then you know to address the wiring on the trailer.

If you find an issue in the trailer wiring it is often easiest to correct this by installing a junction box like # HS381-9000 which includes a new 7-way plug and that also provides connection terminals for joining the existing trailer wiring.

You can refer to the two linked articles for more help with the P2 install and troubleshooting.