2015 GEM eS horn issue

GEM Forum
1

I am working on other issues while I wait on FedEx claim resolution for motor loss.
The horn switch does not work. The signal lights work fine and the wiper works.
I am not getting power to the horn through the harness. The ground wire on the horn works fine. Is that part of the switch bad? Should I get a new switch or should I tap an unused hot wire with a button switch to enable the horn?

2

If one side of the horn switch is grounded and that is what the wiring diagram shows then I would expect the horn has a wire going to it from a fuse, is connected to one side of the horn(marked +) and the other connector on the horn(marked -) would then go to the horn switch.

Did you check the fuse block for the horn power? Wire diagram doesn’t show this?

3

This switch is horn, signals and wiper in one. All else work but not the horn.

4

Short out the horn wires at the miltiswitch assembly. If the horn works the the literal horn switch failed.

If it does not sound then follow the wires with a DMM and see where it’s open.

The circuit is literally a switch and a 2 wire device(a horn) circuit. Trace the loop.

5

I could not find a 2015 wiring diagram but according to a 2013 service manual related to the horn:

Horn does not work.

Visually inspect the fuse F1 or
measure with an ohmmeter to
determine if it is open.
Check voltage circuits, horn, horn
switch (part of the multifunction
switch), and ground.

Replace the fuse if open.
Check for voltage at the horn when pressing the horn
switch. If voltage is not present, check the horn switch
and the circuit. If horn switch is faulty, replace the
horn switch. If horn switch is OK, check the horn, horn
ground and voltage circuit. Use the Horn/Power
Outlet Circuit Diagram and a voltmeter to isolate the
problem.

Here’s the wire diagram… Follow 12V from F1 to light switch to Multi-Function/Horn switch to PSDM to Horn to ground.

GEM-Horn-wire-diagram-2013
GEM-Horn-wire-diagram-2013545×671 33.6 KB

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6

Thanks for the info. I’ll try to work on this tomorrow. I live in Mississippi & it’s been very hot & humid this week.

7

Have you considered installing a WOLO?

8

It’s funny how the engineers made the PSDM such a critical component of the car.

A function as simple as triggering of the horn originates from the keyed fuse F1, exits the PSDM on Plug J3 Pin S (tan wire) and heads to the steering column, goes through the multifunction switch then heads back to the PSDM J3 Pin R (Brn/Gy), Probably triggers a transistor (instead of a relay), then exits the PSDM on Connector J1 (Gy/DB) wire and heads forward to the horn.

I guess this makes for an easier to replace/install wiring harness?
Maybe this engineer could have studied the Vw bug a bit more?

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9

I had paid little attention to what this PSDM was until now since the 2008 has it too. When I saw its description I was asking myself why is this here since it just sounds like a bunch of connectors and fuses. I came to the same conclusion after seeing the horn circuit. ie it’s just to simplify wiring so the harness is made of a few shorter cables with connectors.

Front end harness, including horn goes to the PSDM, steering column harness, including multi-function switch/horn switch goes to PSDM. PSDM just jumpers horn circuit from front to steering column/power. Probably no relay or transistor, just a switch rated at a few amps.

10

I did some checking with voltmeter this morning. The F1 fuse is good. The multiswitch has power at 49a. Head lamps don’t work ( I replaced burnt bulb). I don’t have power at light switch. Still checking but getting hot outside.

Nick Valsamakis

11

An inside view shows the PSDM is actually more than a fuse block. I hesitate to call it a CPU as there is not much processing going on in there. It’s more related to an abacus.

It is still quite important tho-

  • There is some measurement of current on the B- leg that passes through here. (note the shunt). This is for the SOC calculation.

  • The light switching is quite complex as it muxes the rear lights for brake and turn as well as separate front signals.

  • A timer for key off delay, as well as turn signal/4 way flasher.

  • A bit of logic control for the e-brake

  • Serial comms between the Display and motor controller.

1 Like
12

I found that my harness wiring from F1 fuse to the light switch was faulty, I put new wiring from F! to the light switch and continued the connection through the harness. My lights and horn now work.