ker88839_ch11.qxd
1/9/06
11:31 AM
Page 236
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Chapter Eleven
ECM
MODULE
5
EST SIGNAL WHITE
E
BYPASS VOLTAGE TAN AND BLACK
B
7
6 8
3
4
HEI REFERENCE PURPLE AND WHITE
R
2 1
ECM IGNITION GROUND
G
N
+
P
C
DEFINITIONS: 1. 2. 3. 4. 5. 6. 7. 8.
5 VOLT REGULATOR SIGNAL CONVERTER, ALSO CONTAINS BIAS COUNTER / MULTIPLEXER CLOCK OSCILLATOR, KEEPS DATA SYNCHRONIZED CPU (CENTRAL PROCESSING UNIT) PROM SOLID-STATE BYPASS RELAY CURRENT LIMITING MONITOR
+
-
+ PICK-UP
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
GROUND SIDE OF PICK-UP COIL
B
APPROPRIATE GROUND
P
PICK-UP COIL WAVEFORM
E
LESS THAN .5 VOLT SQUARE WAVE
BAT
COIL
-
Figure 11-15. Schematic of the GM HEI magnetic pulse generator ignition system.
If the low data signal is lost, the engine normally starts. If the high data signal is lost, the engine starts, but on default settings from the PCM, Figure 11-22.
PRIMARY AND SECONDARY CIRCUITS 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
