F0:DATA LIST
| No. | Tech 1 Display | Conditions for checking | Nominal value | Trouble Codes | Terminal |
|---|---|---|---|---|---|
| 28 | ENGINE SPEED | Engine running at idle speed, operating temperature switch off all consumers | 670 to 1030 rpm | 19, 31 | 48, 49 |
Note:
The idle speed can be reprogrammed, allowing the output speed to be changed by 50, 100 or 150 rpm.
Perform the following TECH 1 function:
F8:ECU CONTROL RPM CONTROL
and
F6:ADJUSTMENTS IDLE SPEED
| The nominal idle speed may increase when: | |
|---|---|
| the intake air temperature (cf. Data List no. 05) is grater than 50 °C / 122 °F or the battery voltage is very low (between 12.0 and 12.2 V) |
Note:
· In the Motronic M 1.5.4, trouble code 31 is always set when the ignition is switched ON. This code can either be displayed on TECH 1 or flashed out by short - circuiting the diagnostic plug with KM - 640 in switch position "B". When the control unit receives engine speed signals from the inductive pulse pick - up on starting, trouble code 31 is automatically deleted and does not remain stored.
If trouble code 31 is not deleted on starting, a fault is present and trouble - shooting should be commenced.
· Trouble code 19 is only set if there is a very brief interruption of the engine speed signal at engine speeds higher than 2000 rpm.
If the interruption is longer and at engine speeds lower than 2000 rpm, the data stream from the control unit to TECH 1 is interrupted.
Test steps 27 and 28 can be divided into 3 parts
A) Engine does not start, trouble code 31 remains stored
B) Brief engine speed interruption, trouble code 19 may be stored
C) Engine speed deviates from nominal values, no trouble code stored
| Troubleshooting | Nominal value | Cause of Fault |
|---|---|---|
| A) Engine does not start, trouble code 31 remains stored: | ||
| · Check plug connection from inductive pulse pick - up P35 to control unit | firm connection | · Loose contact |
| · Corroded contacts |
· Connect checking spark plug to ignition cable of cylinder 1 and 4
| · Start engine | Checking spark plugs ignite | If no spark |
· Lead interruption from
- ignition coil L2 / Ter. 1 to Motronic control unit K61 / Ter. 1
- ignition coil L2 / Ter. 2 to Ter. 15
- ignition coil L2 / Ter. 3 to Motronic control unit K61 / Ter. 20
- ignition coil to spark plug cylinder 1
| - ignition coil to spark plug cylinder 4 |
· Disconnect Motronic control unit K61 from wiring harness
| · Using multimeter, check resistance at control unit plug K61 / Ter. 48 to Ter. 49 | 0.5 to 0.8 kW | · Pulse pick - up P35 defective |
· Lead interruption or short circuit from
- Motronic control unit K61 / Ter. 48 to pulse pick - up P35 / Ter. 2
| - Motronic control unit K61 / Ter. 49 to pulse pick - up P35 / Ter. 1 |
· Check resistance at control unit plug
K61 / Ter. 48 to Ter. 19 and
| K61 / Ter. 49 to Ter. 19 | infinite W | · Short circuit from |
- pulse pick - up P35 / Ter. 1 to Ter. 3
| - pulse pick - up P35 / Ter. 2 to Ter. 3 | |
|---|---|
| If nominal values are attained | · Toothed disc / teeth corroded |
· Metal chippings on pulse pick - up
B) Brief engine speed interruption, trouble code 19 may be stored:
| · as for A) trouble code 31 | as for A) trouble code 31 | · as for A) trouble code 31 |
|---|---|---|
| · Check shielding on inductive pulse pick - up plug P35 / Ter. 3 on control unit side to ground. | 0 W | · Interference pulses in engine speed signal lead |
· Check that segment disc is firmly seated and undamaged
(removal of oil pan required)
| · Segment disc loose | |
|---|---|
| · Teeth damaged | |
| If nominal values are attained | · Replace pulse pick - up |
C) Engine speed deviates from nominal values, no trouble code stored:
| · See F5:actuator test, test step 04 |