Starter Power Supply

3. Measure acid density of each cell.

Acid Density

Battery

Remarks

ca. 1.28 kg/ltr

Charged

ca. 1.20 kg/ltr

1. car is not used for long time,

2. temperatures are below + 10°C or

3. acid density will not rise in spite of long drive

(Check alternator, regulator, v-belts).

ca. 1.10 kg/ltr

Dead

Charge immediately

4. Checking the acid density also indicates any existing defects in addition to the charge condition.

a — Acid density of one eel! much lower than in other cells: short circuit in discharged cell, battery defective.

b —Acid density of two neighboring cells much lower than in other cells: leak between both discharged cells, battery defective.

c — Acid density in all cells good, but battery voltage drops excessively under load: poor solder connection between cells, battery defective.

5. If necessary, add distilled water to correct level.

18 Checking Battery

Printed in Germany

IGNITION COMPONENTS

Coil

Type/Model

Version

Remarks

928

928 602 503 00 Bosch No. 0 221 122 001

With two resistors, 0.4 ohm and 0.6 ohm

Distributor

Type/Model

Version

Remarks

928

928 602 031 00 Bosch No. 0 237 404 005

Centrifugal advance, vacuum retard

6300 R.P.M. rev. limiting inside control box

Spark Plugs

Type/Model

Version

Remarks

928

Bosch W 145 T 30 Beru 145/14/3 A

Electrode gap 0.7 mm

Control Unit

Type/Model

Version

Remarks

928

928 602 702 02 Bosch No. 0 227 100 008

Transistor ignition

Printed in Germany

Ignition Components 19

CAUTIONS WHEN REPAIRING ELECTRONIC IGNITION SYSTEM

The 928 is equipped with an electronic ignition system. The output of this transistorized coil-type system is so high, that contacting current-carrying components while engine is running could be fatal. Always turn ignition off before doing the following:

1. Connecting engine testers (timing light, tachometer, ignition scope, etc.).

2. Replacement of ignition system parts (spark plugs, ignition coil, distributor, ignition cables, etc.).

Lightning bolts on wiring diagram illustrated below indicate danger spots when engine is running.

Engine Timing Light Circuit Diagram
8 = Tachometer connection

Cautions when repairing Electronic Ignition System

Printed in Germany

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