ST_330_72_1972_Chevrolet_Truck_Chassis_Service_Manual_10_to_30

ELECTRICAL—BODY AND CHASSIS 12-21

RATCHET DOG SOLENOID
RETAINING ASSEMBLY
SCREW
RATCHET
VALVE ASSEMBLY PAWL
MOUNTING SCREW SPRING

FRAME

RATCHET
PAWL

GROOVES
BOTH SIDES

PISTON SPRING
COMPRESSED

INTAKE
VALVE
OPEN

FROM / / "ZTT y/ //'i
WASHER
JAR •ACTUATOR PLA T E

EXHAUST INTAKE STROKE
VALVES
CLOSED

PISTON

SPRING
EXPANDED

INTAKE
VALVE
CLOSED

TO DIRECTION OF T RAVEL
NOZZLES
7 /"7 T
EXHAUST
VALVES ACTUATOR PLA TE
OPEN
EXHAUST STROKE

Fig. 27—Cross Section of W indshield Washer Pump V a lv e

10-30 CHEVROLET TRUCK SERVICE MANUAL

ELECTRICAL—BODY AND CHASSIS 12-22

ELECTRICAL CIRCUIT IDENTIFICATION

Circuit Circuit Circuit Name Circuit Circuit Circuit Name
Number Color Number Color

2 Red Feed, Battery - Unfused 40 Orange Feed, Battery - Fused

3 Pink Feed, Ign. Sw. “ O n” Controlled - 41 Brown-White Feed, Ign. Sw. Accsy. Controlled -

Unfused Fused

3 White,-Purple Primary Ignition Voltage - Dropping 43 Yel low Radio Feed

& Orange Resistor. .38 ohm/ft. 44 Dark Green Instrument and Panel Lights, Feed

3 White-Red & Primary Ignition Voltage - Dropping (Usually Light Switch to Fuse)

Black Resistor 30 ohm./ft. 45 Black Marker and Clearance Lamps

4 Brown Feed. Ign. Sw. Accy. Controlled - (Trailers - ICC Requirement)

Unfused 46 Dark Blue Rear Seat Speaker Feed from Radio

5 Purple Neutral Safety Switch Feed or Single or Rt., Stereo

Neutral Safety Switch to Relay (Truck) 47 Dark Blue Auxiliary Circuits (Trailer)

or Relay to Ignition Switch (Truck) 49 Gray Mod. Assembly to Control

(Auto. Trans.) 50 Brown Blower Switch - Feed

6 Purple Starter Solenoid Feed 51 Yel low Blower Feed - Low

7 Yel low Primary Ignition Resistance Bypass 52 Orange Blower Feed - High

8 Gray Instrument and Panel Lights, 55 Orange Kick-Down on Automatic

(Fused No. 44 Circuit) Transmission

9 Brown Tail and License Lamp, Forward Side 56 Tan Amplifier to Heatsink (Radio)

Marker Lamps 59 Dark Green Compressor to A ir Conditioning
Switch
Tail, Clearance and Marker Lamps

(Trailers) 60 Orange-Black Feed, Battery -

10 Light Blue Dimmer Switch Feed Circuit Breaker Protected

11 Light Green Headlamp, High Beam 63 Tan Blower-Switch Control - Low

12 Tan Headlamp, Low Beam and Feed

13 Purple Front Parking Lamps 65 Purple Blower Motor to Relay

14 Light Blue L.H. Indicator and Front 70 Red-White Feed, Relay Controlled
Circuit Breaker Protected
Direction Light

15 Dark Blue R.H. Indicator and Front 72 Light Blue Blower Switch Medium to Blower

Direction Light Resistor

16 Purple Direction Signal Switch, Feed 75 Dark Green Back-Up Switch or Parking Brale

from Flasher Alarm Feed

17 White Direction Signal Switch, Feed 80 Pink-Black Feed-Key Warning Buzzer

from Stop Switch 90 Pink-Black Feed, Cutout Sw. Controlled

18 Yel low Stop and Direction Lamp or Circuit Breaker Protected

Direction Lamp Only-Rear L.H. 91 Black Windshield W iper - Low

19 Dark Green Stop and Direction Lamp, or 92 Light Blue Windshield Wiper - High

Direction Lamp O nly - Rear R.H. 93 Yellow Windshield Wipfer Motor Feed

20 Red Stop Lamp (Trailer) 94 Dark Blue Windshield Washer Switch to

22 White Ground - Direct (Trailer Wiring) Windshield Washer

24 Light Green Back-Up Lamp 101 Dark Blue Resistor Output to Blower Relay

25 Brown Generator or Generator Armature 102 White SI Alternotor Regulator Sensing

to Voltage Regulator “ A ” (Includes Circuit

Generator Telltale Circuit) or 105 Black Ammeter - Generator

Regulator to Ignition Switch (Truck) 106 Black-White Ammeter - Battery

26 Dark Blue Field Circuit (F) (Gen. Reg.) 107 Dark Blue Over-Speed Warning Light

27 Brown Traffic Hazard Switch, Feed from 111 Black Buzzer to Low A ir Pressure or

Flasher Vacuum Switch

28 Black Horn Switch 112 Dark Green Telltale Temperature Gauge (Hot)

29 Dark Green Horn Feed White

30 Tan Fuel Gauge to Tank Unit 119 White Generator (Alternator) to Regulator

31 Dark Blue O il Pressure - Engine 120 Black Power Trans. Relay to Thermo

32 Yel low Map Light Switch (Truck)

33 Tan Warning Light - Brake Alarm 121 Brown Tachometer to Coil

34 Purple Fog or Drive Lamp 124 Black Switch on Shift Lever to Adapter, or

35 Dark Green Telltale Temp. Gauge (Hot), or Std. to Motor on Rear Axle (Low), or

Temp. - Readable Gauge. to Adaptor (Low) (Truck)

38 Dark Blue Flasher, Fuse Feed 125 Light Green Switch to Diff. Lock-Out Valve (Truck)

39 Pink-Black Feed, Ign.Sw. “ O n ” Controlled 126 Brown Diesel Ignition - Buzzer to No. 4

Fused “ L” on Voltage Regulator (Truck)

10-30 CHEVROLET TRUCK SERVICE MANUAL

ELECTRICAL—BODY AND CHASSIS 12-23

ELECTRICAL CIRCUIT IDENTIFICATION (Cont’d.)

Circuit Circuit Circuit Name Circuit Circuit Circuit Name
Number Color Number Color

127 Dark Green Two-Speed Axle - Switch on Shift 181 Light Blue Power Seat - Solenoid -

Lever to Motor on Rear Axle Fore and Aft

(High) (Truck) 182 Yellow Power Seat - 6-W - Aft and Down

130 Color depends Generator (Alternator) External 183 Light Blue Tailgate - Window - Up

on Resonator Resistance 184 Tan-White Tailgate - Window - Down

Brown-White 2 ohms per foot 189 Dark Green Power Seat - 4-W - Fore

Black-Pink 1 ohm per foot and Down

131 Brown Low Vacuum to A ir Pressure 190 Yel low Power Seat - 4-W - Aft and Up

Warning Light to Switch (Truck) 191 Light Green Power Seat - 4-W - Solenoid -
Feed, Ign. Sw. “ O n ” Controlled -
139 Pink-Black Up and Down

Fused 192 Purple Defogger - High or Single Speed

140 Orange Feed, Battery - Fused 193 White-Purple Defogger - Low Speed - .38 ohm/ft.

141 Brown-White Feed Ign. Sw. Accsy. Controlled & Orange

Fused 198 Light Green In-Car Sensor to Control
Ground Circuit - Direct
150 Black 199 Brown Rear Seat Speaker - Feed from Radio

151 Black Ground Circuit - Direct Left Stereo

152 Black Ground Circuit - Direct 200 Light Green Front Speaker - Feed from Radio -

153 Black Ground Circuit - Direct Single or Right Stereo

154 Black Ground Circuit - Direct 201 Tan Front Speaker - Feed from Radio -

155 Black Ground Circuit - Direct Left Stereo

156 White 202 Black Compressor Overheat Switch to

157 W hite Black Ground Circuit - Sw. Controlled - Thermal Limiter

Body Interior Lamps - such as 203 Red/White Rear Air Conditioning Potent­

158 White-Dark Dome, Courtesy, Map, Warning,etc. iometer Feed

Green 204 Brown Ambient Temperature Switch to

159 Black-Purple Ground - Key Warning Buzzer Thermal Limiter (Feed)

162 Gray Power Top-Up 205 White/Black Seat Belt Seat Sensor to Belt

163 Purple Power Top-Down Retractor (Grd.)

164 Dark Blue Window Control-L.F. - Up 206 Black Neutral Start Switch to Buzzer

165 Brown Window Control-L.F. - Down and Lamp

166 Dark Blue Window Control-R.F. - Up 207 Yellow/Black Seat Sensor to Neutral Start

White Switch

167 Tan Window Control-R.F. - Down 208 Black Switch Controlled Ground (TCS)

168 Dark Green Window Control-L.R. - Up 209 Purple Parking Brake Warning Lamp

169 Purple Window Control - L.R. - Down 239 Pink-Black Feed, Ign. Sw. “ O n ” Controlled -

170 Light Green Window Control - R.R. - Up Fused

171 Purple-White Window Control - R.R. - Down 240 Orange Feed, Battery - Fused

178 Dark Green Power Seat - 6-W - Fore and Aft 241 Brown-White Feed Ign. Sw. Accsy. Controlled -

179 Tan Power Seat - 6-W - Solenoid - Rear - Fused

Up and Down 252 Gray Electric Door Lock (Unlock)

180 Light Green Power Seat - 6-W - Solenoid - Frt. - 253 Light Green Electric Door Lock (Lock)

Up and Down 340 Orange Feed, Battery - Fused

NOTE: Ground circuit numbers used in the order as listed, depending on the number of circuits at any one time.
* When No. 35 circuit does not apply (normally on Vehicles with both Telltale Light and Standard Temperature Gauge.)

10-30 CHEVROLET TRUCK SERVICE MANUAL