0105 - Checking the anti-jerk, ARA and/or electronic idle speed control, ELR Engines 601, 602.91, 603.91 (note deviations for off-road vehicles)

07.1-105 Checking anti-jerk control (ARA) and/or electronic
idle speed control (ELR)

Test and adjustment data

1) Automatic transmission
2) Manual transmission

Fault memory

Only short-circuit faults detected on control units with "RO1".
Control units with "RO2" also detect open circuits.
Production breakpoint: Control unit with "RO2" May 1988.

The number of pulses indicates whether and which component is faulty or whether components in the control circuit are faulty.
No system diagnosis is possible on vehicles with Bosch ARA control unit.

Special tools

Commercially available testers

Additionnal testers

Function diagram anti-jerk control/idle speed control

P07.10-0224-57

Connection diagram of pulse counter of hand held tester

Pulse counter

Black cable Circuit 31 (gnd) or socket 1

Red cable Circuit 15 (ignition), circuit 30 (battery) or socket 16

Yellow cable Socket 4 (AJC, ESC/AJC control module)

Hand held tester

Black cable Circuit 31 (gnd) or socket 1

White cable Circuit 15 (ignition) or socket 16

Red cable Circuit 30 (battery), X4/10 (terminal block) or socket 3

Yellow cable Socket 4 (AJC, ESC/AJC control module) )

a) Test of engine 601.911/912 up to 01/93
Engine 602, 603

Testing components

-------------------------------

Test overvoltage protection (K1/1)

Check fuse on overvoltage protection. Activation according to electrical wiring diagram.

Switch on ignition, pull off control unit (N8 or N8/1) and measure voltage between the jacks (9 and 11).

Display: approx. 12 V DC

End of test

Yes

No

Impulse display "2"

Yes

No

Checking speed sensor
Engine switched off. Pull off double coupling (L3x). Connect multimeter to pins of double coupling and press key "W". Measure resistance.

Display: AB Elektronik 1000  10W
Beru 530  10W
VDO 1900  10W

Renew starter ring gear speed sensor (L3).

End of test

Multimeter connection as above, press key "V". Run engine at idle speed.

Display: > 4 V AC
Voltage rises with increasing speed.

Inspect starter ring gear speed sensor for accumulation of dirt or metal chips, clean if required.

Yes

No

Impulse display "3"

End of test

Check voltage on 1-pole coupling "Ignition" On.

Display: approx. 5 V

Renew coolant temperature sensor.

Yes

No

Checking coolant temperature sensor (B11/1)
Engine switched off. Pull plug off temperature sensor and check resistance against ground. Set values see diagram. Measure resistance at two temperature measuring points.
Example:

+20 °C=2,2-2,8 kW

+80 °C=290-370 W

Eliminate line interruption. Renew control unit (N8 or N8/1).

End of test

Yes

No

Impulse display "5" (function check)

End of test

Until 08/89

Increase engine speed to 900/min.
Briefly actuate control lever several times, short misfiring is noticeable.
"ARA operational".

Check lines according to wiring diagram. Check fuse of overvoltage protection K1/1.

If lines are OK, renew control unit ELR (N8/1 or N8/2).

Pull double coupling off ARA electromagnetic actuator (Y22/3).
Briefly connect battery voltage to ARA electromagnetic actuator (Y22/3) (max. 3 s).

Idle speed drops.

Renew electrom. actuator.

End of test

Yes

No

Yes

No

As of 09/89

Check voltage on double coupling of ARA electromagnetic actuator:
Press multimeter key "V=".
Engine idling - briefly accelerate full throttle.

Voltage rises.

Yes

No

Impulse display "6"

Engine idling. Pull double coupling (arrow) off ELR electromagnetic actuator (Y22) for at least 3 s and reconnect.

Upon reconnecting, the idle speed briefly exceeds the governed idle speed.

Apply battery voltage to ELR electromagnetic actuator (Y22) for a maximum of 3 s.
Caution! If the voltage is applied for longer than 3 s, the ELR electromagnetic actuator will be damaged.

Idle speed rises.

Renew electrom. actuator.

End of test

End of test

Yes

No

Yes

No

Engine idling. Remove double coupling (arrow) from electromagnetic actuator (Y22).
Connect multimeter and set to "V=".

Display: approx. 12 V

Yes

No

Check lines according to wiring diagram. Check fuse of overvoltage protection relay K1/1.

If lines are OK, renew control unit (N8/1).

Loosen lock nut and adjust idle speed (arrow).
left = higher
right = lower

End of test

Engine idling. Pull double coupling (arrow) off ELR electromagnetic actuator (Y22).

Check idle speed.

Set values:

Engine Idle speed/min

601 66040

602 62040

603.912+603.913

with automatic transmission 58040

603.913

with manual transmission 62040

Yes

No

Pulse display "7" and "9" see section "b" test of engine 601.912 as of 02/93, 601.913.

Checking individual adjustment plug (R18/3)
(if available)

End of test

Display: approx. 5 V

Individual adjustment plug (R18/3)
Engine switched off. Pull individual adjustment plug off double coupling.
Glow starter switch in position "2". Set multimeter to "V=" and measure voltage.

Eliminate line interruption.

Renew individual adjustment plug (see table).

Yes

No

Table individual adjustment plug

Note
In order to change the individual adjustment plug it is necessary to switch off the "ignition" as the new adjustment will otherwise not be identified by the control unit.
In order to establish the amount of the resistance it is possible to simulate the adjustment plugs in the above table with the ohm decade.

b) Testing engine 601.912 as of 11/92,
Engine 601.913

1) Voltage rises as engine speed rises

2) Measured at 20 °C ambient temperature (each 10 °C change in ambient temperature alters resistance by 4 %)

3) Air guide housing removed