Hella Supertone Horns DIY Installation on a G10

D.I.Y Section

Hella Supertone Horns DIY Installation on a G10

Postby gohch on August 21st, 2009, 5:23 pm

I thought I share what I did when I discovered that the G10 Altis horn was quite soft ](*,). I did some research on the subject and noticed that the 2 common options were Stebel Magnum 2 or Hella Supertones. I choose the Hella Supertones for the 118 dB published specs which was twice as loud as the Stebel Magnum 2 (published at 115dB).

The few considerations I had for performing the modification was:
  1. DIY-able
  2. Minimal changes to the original equipment (with the exception of removing the stock horn)
As I inspected the engine compartment for the mounting location (where the stock horn was), the following were noted:
  1. the Hella horns to be too big to fit through the gap into the space between the radiator and the front grille, making this install tougher. There was many other ways, e.g. removing front grille, removing entire front bumper etc. I finally settle on using the access that the fender liner gives (read page 301 of the G10 Altis user manual). The method of locating the horns will be through a string lower from the gap and tied to the horn that is positioned through the access from the dismounted fender liner.
  2. there was already cabling provisions for a second horn on the driver side. I guessed also that since the cabling was provisioned, that Toyota would also provide the relay required to drive a pair of horns; the manual vaguely refers to 2 fuses in the engine compartment (Nbr 7 - 50A and Nbr 30 - 10A on page 293 and 294 respectively of the G10 Altis user manual). This will save the need for additional wiring. Almost plug and play.
Installation Time
1 hour 15 minutes

Parts Required
  1. Hella Supertone horns (Qty: 1 pair 300Hz/500Hz) – [$55.00/pair, Lian Siong Corporation Pte Ltd, Blk 633, #01-120 Veerasamy Road Singapore 200633. Telphone: (65) 6296 4550]. The horns package comes with a SPST relay that consists of a coil (terminals 85 & 86), 1 common terminal (30), and one normally open terminal (87). This relay will not be used.
  2. M8 hexagonal bolts with washers (Qty: 2) – [$0.50, regular hardware stores]
  3. Wire terminals (Qty: 2 females + 2 M8 rings) – [$0.30/ea, Sim Lim Tower electronics shops on the 3rd level]
Total cost of parts is $57.20.

Tools & Supplies
  1. Pliers
  2. Crimping tool (if you have one, otherwise use the pair of pliers)
  3. Hex ratchet wrench or ring/open/adjustable spanner sized for M8 hexagonal bolts/nuts. Typically this is a size 12mm socket. 10mm socket are also useful for working on some of the other bolts in the engine compartment. So, it might be good to have a 10x12 ring spanner/wrench handy.
  4. #2 Philips screw driver
  5. Wire cutter
  6. Smooth file
  7. Scissors or knife
  8. Torch light (optional)
  9. Spray paint, black matt
  10. Fishing line or heavy string
  11. 16cm of AWG14 wire


My next 2 posts will detail the preparation and installation steps.

STANDARD DISCLAIMER: I do not know if doing this modification will void Borneo Motors' warranty, neither do I warrant the steps that I have used and documented here for suitability or any other purposes
Last edited by gohch on August 21st, 2009, 5:55 pm, edited 1 time in total.
Posts: 71
Joined: March 24th, 2009, 6:01 pm

Preparation Steps

Postby gohch on August 21st, 2009, 5:32 pm

A. Paint the Hella horns black
  1. Unscrew 8 mounting bolts and nuts (use the #2 Philips screw driver) from Hella horns and remove red protection grilles from the horn. Use a pair of pliers to hold the nuts when loosening, if necessary. Horns will be disassembled, so use 2 of the removed bolt and nuts to secure the horns’ halves to prevent separation. Take care to ensure that the paper washer on the horn that was assembled between horns and the grilles is kept intact.
  2. Spray the red protection grilles with matt black paint to subdue its appearance after installation. Leave spray paint to dry and cure on the grilles, preferably 24 hours.
  3. Mount and secure the painted grilles on the horns; ensure that the bolt and nuts are secured fastened. Use a pair of pliers to hold the nuts when tightening, if necessary.

B. Built and install the Hella horns’ ground wire assembly
  1. Cut two 8 cm length of AWG14 wire and bare 0.5 cm of the wires at both ends.
  2. Crimp (with a pair of pliers or a crimping tool) 1 female terminal at one end and a an M8 ring terminal at the other end for both wires
  3. Connect the female terminal to the terminal post with the silver seal, on each of the horns.
  4. Replace prepared horns in its packaging.
Note: the bolts and nuts are mounted keep the ground leads in place only, no other purpose.
Posts: 71
Joined: March 24th, 2009, 6:01 pm

Installation Steps

Postby gohch on August 21st, 2009, 5:43 pm

A. Disconnect the battery negative connector.
  1. Switched off the car’s engine, if not already so.
  3. Disconnect the negative battery connector from the 12V battery. Use the wrench/spanner to loosen the connector’s tightening bolt/nut if necessary. PLEASE NOTE THAT THIS MAY RESET SOME OR ALL OF THE SETTINGS IN THE CAR AND/OR OTHER ELECTRICAL OR ELECTRONIC EQUIPMENT INSTALLED IN THE CAR. Most commonly, some or all setting in the ICE will be reset. The onboard computer that maintains the fuel consumption readings, engine run time etc will also be reset.

B. Remove the stock horn on the passenger side.
  1. Locate the stock horn on the passenger side of the engine bay in the space between the front grille and the radiator. It is attached by a black bolt to the cross beam.
  2. Tie a length of line/string to the stock horn to prevent it from dropping.
  3. Use the 12mm socket wrench/spanner to loosen the bolt that secures the stock horn. When loosen, use finger to undo the bolt while holding onto the horn.
  4. Disconnect the stock positive connection from the stock horn by pressing on the clip lock and pulling the connector away from the horn. Secure the connection at a known location with some line/string.

C. Locate and extend stock horns’ driver side positive lead.
  1. Cut the cable tie that secures the lead
  2. Extend the lead sufficiently by estimating the position of the mounted Hella horns.
  3. If needed, secure the lead with some line/string.

D. Create a proper ground return
  1. Use a metal file to remove sufficient paint from the location surrounding the mounting hole. This is for a proper and good ground of the horn.
  2. Do for both the left and right mounting points.

E. Partially dismount passenger side fender liner
  1. Locate the 2 self-tapping screws that secure the fender liner to the front bumper. These 2 screws and a push plug/clip secure the fender liner. Refer to page 301 of the car manual.
  2. Use the 10mm socket wrench/spanner to loosen the screws.
  3. Free the fender liner from the front bumper mounting lip to allow access the lower part of the space between the radiator and the front grille.

F. Position Hella horns on engine splash-guard.
  1. Secure a 1.5m line/string to an engine compartment point.
  2. Lower the line/string into the space between the radiator and front grille, and onto the engine splash-guard.
  3. Shift the line/string towards the right side of the bumper using a short stick/rod/screwdriver.
  4. Reach into the space between the radiator and front grille from the access created from the partially dismounted fender liner.
  5. Tie one Hella horn with the line/string and place the horn through the same access, onto the engine splash-guard. (The horns should be visible from the top of the engine compartment.
  6. Raise the Hella horn using the string and secure the line.
  7. Repeat with the other Hella horn using the same technique after mounting the first.

G. Mount both Hella horns
  1. Work on the driver side horn first.
  2. Connect the FEMALE terminal from the stock horns’ positive lead to the remaining terminal post (terminal post with the copper seal).
  3. Place a bolt and washer through the ring terminal from the horn’s negative lead followed by the mounting bars and loosely secure the combination to the cross beam.
  4. Dress the negative lead so that it does not interfere mechanically in the immediate area.
  5. Mount the horn securely by tightening the bolt to the cross beam.
  6. Remove the line/string from step (2).
  7. Mount the passenger side horn using the above steps.

H. Reconnect the battery’s negative connector to its negative terminal.

I. Test the newly installed Hella Supertone [super loud] horns.

J. Remount passenger side fender liner
  1. Re-engage the fender liner with the front bumper mounting lip and align both screw holes.
  2. Reset the 2 self-tapping screws in the original screw holes.
  3. Use the 10mm socket wrench/spanner to re-tighten the screws.
Posts: 71
Joined: March 24th, 2009, 6:01 pm

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