Primary and Secondary Circuits

6 ECM

5 EST SIGNAL WHITE

BYPASS VOLTAGE TAN AND BLACK E

B 7 MODULE

8

3

4

ECM IGNITION GROUND HEI REFERENCE PURPLE AND WHITE R

G 2

1

DEFINITIONS:

1. 5 VOLT REGULATOR 2. SIGNAL CONVERTER, ALSO CONTAINS BIAS 3. COUNTER / MULTIPLEXER 4. CLOCK OSCILLATOR, KEEPS DATA SYNCHRONIZED 5. CPU (CENTRAL PROCESSING UNIT) 6. PROM 7. SOLID-STATE BYPASS RELAY 8. CURRENT LIMITING MONITOR

TERMINAL VOLTAGE VALUES:

C PRIMARY IGNITION PATTERN G LESS THAN 100 Mv (DC VOLTAGE)

+ BATTERY VOLTAGE R 5 VOLT OR 12 VOLT SQUARE WAVE N P + C

PICK-UP

+ BAT COIL

N GROUND SIDE OF PICK-UP COIL B APPROPRIATE GROUND

P PICK-UP COIL WAVEFORM E LESS THAN .5 VOLT SQUARE WAVE

Figure 11-15. Schematic of the GM HEI magnetic pulse generator ignition system.

Ifthelowdatasignalislost,theenginenormally starts.Ifthehighdatasignalislost,theengine starts,butondefaultsettingsfromthePCM, Figure 11-22.

The general operation of the ignition primary circuit and some of the system components have already been covered.

The secondary circuit must conduct surges of high voltage. To do this, it has large conductors and terminals, and heavy-duty insulation. The secondary circuit in a distributor ignition system, Figure 11-23, consists of the: • Coil secondary winding • Distributor cap and rotor • Ignition cables • Spark plugs The secondary circuit in a distributorless ignition system (DIS), Figure 11-24, consists of the: • Coil packs • Ignition cables, where applicable • Spark plugs The secondary circuit in a coil over plug DIS consists of the same components as a DIS system except that each cylinder has its own separate coil