BOSCH Car Alarm


Installation and operating instructions


For motor vehicles with 12 V electrical system and negative battery terminal to ground Priming takes place by means of an infrared remote control unit.

Triggering alarm when system primed:

When system not primed:

Acoustic alarm is given off via a separate alarm horn or siren which sounds continuously for a max of 30 seconds.

Optical alarm (not officially authorized for general use in Switzerland) for identification of the vehicle is for a max of 5 minutes via the turn-signal lamps (via an auxiliary relay, not included in the scope of delivery).

Alarm repeat.

If a new signal occurs at the alarm inputs after completion of the 30 second long acoustic alarm, the acoustic alarm sounds once again The optical alarms is likewise restarted or extended.

Ignition contact break (for spark-ignition engines),

starting lock (for diesel vehicles) Via enclosed relay which normally blocks the ignition voltage supply or starting-motor voltage supply Observe "Emergency measures" note.

Priming lock.

To avoid undesired priming, priming of the alarm system is not effective when the ignition is switched on.

Alarm stop.

Immediate by switching off the alarm system via the infrared remote control unit Otherwise, the alarm stops after completion of the legally stipulated duration of alarm.

Auxiliary systems (order separately).

The scope of protection is extended by Protection against wheel theft and against being towed away or loaded, "Plus 3". This is connected to the alarm inputs S- and S1-.

Interior protection, "Plus 4", which is connected to the alarm input T-.

Legal requirements

The Bosch Car Alarm 20i complies with the BAV* of September 27, 1969 with the amendment to Article 34, Section 5 of November 21,1979 and the ECE Regulation No 18/Rev 1 of November 24,1980

* FRG-specific (not Switzerland)

Scope of delivery

Electronic alarm relay K1, evaluation electronics K5, preamplifier (receiver) N, handheld transmitter (infrared remote control unit), 4 ground-switching contact switches S5, relay K2, perforated strips, electric leads, bits and pieces.

Special accessories (order separately) blocking diode (V) 0212911001, relay for starting lock(K6) 0 332 014150, relay for optical alarm () 0332015001 (not officially authorized for general use in West Germany).


Screwdriver, open-end wrench 13 mm, hammer, center punch, electric drill, drill bit dia 3.6/10 mm, bording bit, crimping pliers for blade receptacles, side cutting pliers, test lamp.

Installation recommendations

Loosen negative terminal of battery.

The alarm relay K1 and the evaluation electronics K5 are mounted at an inconspicuous heat - and water-protected position, preferably under the instrument panel, with blade-connector contacts inclined downwards.

Receiver N should be positioned so that there is good Ime-of-sight connection between it and the transmitter (infrared remote control unit) outside to vehicle. Select the installation position so as to avoid exposure of the receiver to direct sunlight (otherwise there will be a decrease in range). Recommendation Installation in the center console or in the center of the instrument panel between the cockpit and glove compartment If direct sunlight cannot be avoided when actuating, the user should position his body so as to cast a shadow on the receiver.

Mount the contact switches S6 or S7 for the hood lid and trunk lid at a suitable position, so that when lid is closed, the contact switch is sure to be open, cannot be blocked form outside and so that the leads cannot be disconnected If necessary, use the enclosed perforated strips for fastening the switch In vehicles with engine-compartment lightings and trunk lighting, these switches may be used, if connected to ground.

Caution: Both the lamps for engine-compartment lighting and trunk lighting must be fed from the positive connection (+) terminal 30 If necessary, reconnect lamps.

All doors must be provided with door contacts. If necessary, retrofit enclosed door contacts S5, or procure original door contacts from vehicle dealership. Mount relay K2 for starting block and ignition contact breaking facing downwards. Mount alarm horn, siren B1 additionally in the engine compartment so that access to them can be gained from outside but not from beneath.

If a main battery switch is installed in the vehicle, this must not be switched off since the alarm system is otherwise rendered ineffective.

Lay all leads so that they cannot be seen.

Electrical connection

Disconnect negative terminal of battery. Make certain of good ground connection to ground.

Alarm relay K1

The enclosed cable harness with multiple plug X is attached to alarm relay K1. The individual leads are then connected to the connecting points in the vehicle, as listed below, and cut to length, provided with the necessary multiple butt connector and connected up.

Terminal to alarm relay K1 Lead colors Connecting point
A gray /red Alarm horn B1
red Fuses F1, K1. 30
E yellow Evaluation electronics K5, K1. E
S- black Trunk switch S6
S1- blue Engine-compartment switch S7
T+ green Door-contact switch S9, switches to positive
T- white Door-contact switch S5 switches to ground
V red/yellow Relay K2, K1. 85
15 red/black Ignition and starting switch S2, K1. 15
30 red Fuses F1, K1. 30
31 brown Vehicle ground W

The black/green lead is used for the optical alarm.

Provide the end of the lead coming from term 31 of the alarm relay with an electric terminal (dia 5 mm) and apply to vehicle ground. Term 15 of the alarm relay must be connected to the lead coming from term 15 of the ignition and starting switch S2. To do this, use the enclosed coming from term 30 and term. must be run via the fuse box F with separate 8 A fuse.

Receiver N is connected to the evaluation electronics K5 at term 1...4.

The evaluation electronics K5 is connected using the enclosed blade receptacles. Term D+ is connected to term 15 of the ignition and starting switch. This connection prevents the alarm system from being primed when the ignition is switched on. Term E and term 30b are connected to the alarm relay K1. Term 31 is connected via the radio casing or directly to vehicle ground.

Door contacts S5 and S9.

Connect door contacts S5, which switch to negative (-), to term T- of the alarm relay (e g VW/Audi, BMW, Ford, Opel) . Connect door contacts S9, which switch to positive (+), to term T+ of the alarm relay When the voltage differs at the front-door and rear-door contacts, "negative-controlling" contacts must be connected to T- and "positive-controlling" contacts to T+ of the alarm relay If the car is broken into, the door which is opened first activates the alarm.

In Mercedes-Benz vehicles, always connect |the door contact at the front right to the alarm relay. The electrical connection is made using the enclosed branch connector. Blocking diode V (order separately) may possible be applied in vehicles with a special interior light above the rear seat bench and with voltage at all door contacts, so that when the rear interior light is switched on the front interior light does not light up. Connect alarm horn B1 to term A of the alarm relay (only one horn) If connecting several horns or a fanfare horn, do so via a relay. The lines leading to the alarm horn must be laid separately for the purpose of optimum interference suppression. The connection is made using the enclosed non-insulated blade receptacles which must be covered with protective rubber caps. Secure the ground cable to vehicle ground using lug M8.

Horn switch S4 switches to negative (-).

Connect in accordance with illustration 4. Horn button S4 switches to positive (+). Connect in accordance with illustration 5. Use of the signal horn or of the fanfare horn fitted as standard m the vehicle is not recommended, since these are usually easily accessible from outside and can therefore be easily disconnected.

Contact switches S6 or S7 ground-switching for hood and trunk lid which are independently fused must be connected to term S- and S1- of the alarm relay. The connection is made using the enclosed, non-insulated blade receptacles.

Relay K2 for starting block and ignition contact breaking is connected using the enclosed insulated blade receptacles to term 30,85,86 and through a blade receptacle with branch to term 87. Connect the lead coming from term 86 of relay K2 to the lead coming from term 15 of the ignition and starting switch using a branch connector. Short circuit the connection lead present from ignition and starting switch S2 to ignition coil T (term 15) or to starting motor M (term 50) and run this via relay K2 (term 30 and term 87).

Vehicles with catalytic converter.

In addition to the ignition contact break, a starting lock should be installed in vehicles equipped with catalytic converters, m order to prevent damage to the catalytic converter by unburned fuel (m case an attempt is made to start the vehicle after break-in) Installation is according to the diagram.

Relay (not m scope of delivery) is used for vehicle recognition through optical alarm.

In accordance with the presently valid ECE R18 and the regulations in a number of countries (not West Germany), the low-beam headlamps may flash for 30 seconds i in each case.

Signal using turn-signal lamps.

Connect term 86 to seperately fused positive lead term 30 via a branch connector. Relay (not included in scope of delivery) is used for optical alarm vehicle identification.

Signalling using low-beam headlamps.

Radio protection. The ground cable of the evaluation electronics is not directly applied to the vehicle ground, but to the metal casing of the radio. This is done in such a way that when the radio is pulled out, this ground cable will always be disconnected from the vehicle ground .The alarm is activated even if the system is not primed and for this reason, disconnect the t battery when removing the radio.

Auxiliary systems.

Terminal Z at the alarm relay is for connecting auxiliary devices e. g. Protection against wheel theft and against being towed or loaded "Plus 3" or Interior protection "Plus 4". Installation instructions are enclosed with the auxiliary systems.

Interference voltages.

The supply leads (terms 15, 30, and 31) of alarm system are insensitive to the interference voltages (max 100 V/5 ms) which customarily occur in the vehicle.

In the case of special installations, which e g are switched via the door contacts and hood contacts, cutoff voltage peaks (e. g. at undamped relays) may occur and bring about interference at term S-, S1-, T-, T+. In such cases, exchange the relay of the special installations for a relay with parallel resistance or a diode.


Check the complete installation and line connections. Disconnect battery. Check all the possible functions of the alarm system (see "Function").


When using the infrared remote control unit, the transmitter must be directed towards the receiver mounted inside the vehicle. To prime, press the blue non-locking push-button on the remote control unit. This is indicated by a red light-emitting diode on the transmitter. When the signal is identified by the receiver, this is confirmed through the flashing of the red indicator lamp at the receiver for 3 seconds.

Unpriming is carried out in the same way, however, this is not indicated by the indicator lamp flashing, it lights up continously for 3 seconds. There must be no nontrans-parent obstacle between the receiver and the transmitter If the signal is not received the first time, then the procedure should be repeated after a delay. This time the button on the hand-held transmitter should be released and pressed again while slowly moving the hand-held transmitter vertically back and forth in the direction of the receiver.

Attention: During the 3 seconds that the red indicator lamp is flashing or is continuously lit, no switch-over is possible If the range (transmitting power) clearly decreases, the button cells (e g Varta V 675 PX) in the infrared remote control unit must be replaced. To do this, loosen the Phillips head screw at the remote control unit, remove lid and exchange button cells.

Emergency measures

If the battery is weak or if there is a defect in the alarm system, e g due to poor contact, a blow fuse or something similar, it is no longer possible to start the vehicle. Under some circumstances, this may also lead to activation of the alarm.

(In this case, the blade receptacle must be re-connected form term 30 of relay K2 to the branch lug of the blade receptacle at term 87 of relay K2 and, if necessary, the multiple plug of alarm relay K1 must be disconnected.

These installation instructions are not binding. We recommend that you re-check the possibilities for installation.

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1. Complete diagram
2-3. Special circuitry for rear interior light
4. Horn button, switches to negative
5. Horn button, switches to positive
6. Starting lock
7. Optical signal (turn-signal lamps)
8. Optical alarm (low-beam headlamps)
9. Radio protection
10. Diagram of operating principle

Legend Figs.

A1 Radio
A2 Car Alarm "Plus 3"
A3 Car Alarm "Plus 4"
B1 Alarm horn
B2 Signal horn, standard
E1 Turn-signal lamps
E2 Interior light, front
E3 Engine-compartment lamp
E4 Trunk lamp
E5 Interior light, rear
E6 Interior light, front with switch
F Fuses
G1 Battery
K1 Alarm relay
K2 Relay for ignition and starting block
Relay for optical alarm
K4 Time relay
K5 Evaluation electronics
K6 Relay for starting lock
M Evaluation electronics
N Receiver
S2 Ignition and starting switch
S3 Turn-signal switch
S4 Horn button
S5 Door-contact switch, ground-switching
S6 Trunk switch
S7 Engine-compartment switch
S8 Switch for interior lamp, rear
S9 Door-contact switch, positive-switching
Ignition coil
V Blocking diode
W Ground
X Multiple plug

Lead colors

bl blue
ge yellow
gn green
rt red
gr grey
sw black
ws white
br brown