G10502
Stall Warning System Schematic  515 
27-32-0  Figure 2  Aug 01/74 
Page 6 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

STALL WARNING SYSTEM - TROUBLE SHOOTING
1. General
A.  In the following trouble shooting charts; all possible failures are listed under TROUBLE column. The PROBABLE CAUSE column lists failures in airplane wiring and failures of whole components only. The component assumed most likely to fail is the P5-18 stall-warning module; therefore in trouble shooting the system it should be replaced first.
B.  The continuity checks listed are from one component to another. It may be easier or necessary to check continuities to the connectors between the listed points. In that case the wiring diagram should be used to determine what connector and pin to check. Refer to wiring diagram 27-32-11 in Wiring Diagram Manual for pin numbers and part numbers referred to in trouble shooting chart.
C.  The trouble shooting procedure is divided into several charts to cover system failures occurring under various airplane conditions as follows:
(1)  
Airplane on ground, No. 1 engine not running, system toggle switch in NORMAL position.

(2)  
Airplane on ground, No. 1 engine off, system toggle switch in TEST position.

(3)  
Airplane on ground, No. 1 engine running, system toggle switch in NORMAL position.

(4)  
Airplane in air, system toggle switch in NORMAL position.

D.  Before any extensive component and airplane wire trouble shooting, examine system power at circuit breakers, bent or loose connector pins, metallic or other contamination in connectors, etc.
501 
Feb 20/87  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  27-32-0 Page 101 

2.  Trouble Shooting Charts (Stall Warning System)
A.  Airplane Condition: Airplane on ground, No. 1 engine not running, switch (S1) in NORMAL position.
TROUBLE  PROBABLE CAUSE  ISOLATION PROCEDURE  REMEDY 
OFF indicator does not illuminate OFF indicator comes on but master caution lights do not Shaker shakes  P5-18 stall warning module No voltage at pin 20 (disconnect D213) Burned out indicator light bulbs No short circuit continuity between pin 14 and 15 of D213 Not ground on pin 4 of D213 P5-18 stall Warning module No short circuit continuity between P5-18 pin 21 (D213) and P5-19 Pin 27 (D483)P5-19 Test Module Master caution systemP5-18 stall warning module  Assure power through circuit breaker C313 on P6 panel and continuity from load side to pin 20 (D213) Establish wire continuity per Wiring Diagram 27-32-11  Replace module Replace circuit breaker or repair wiring Pull out top of OFF indicator. Replace bulbs Replace landing gear module M338 on shelf E2-2 if necessary Establish ground Replace module Establish continuity Replace P5-19 module Trouble shoot master caution system (Chapter 31) Remove and replace 

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27-32-0  Feb 20/87 
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B. Airplane Condition: Airplane on ground, No. 1 engine off, switch (S1) in TEST position.
TROUBLE  PROBABLE CAUSE  ISOLATION PROCEDURE  REMEDY 
OFF indicator does not go off OFF indicator does not come on when master test switch (P2-1) is in TEST position  P5-18 stall warning module No 28 volts dc at pin 3 (D213) No ac power at pin 27 (D213) No ground at pin 26 (D213)No short circuit continuity between pin 7 (D213) and pin 2 (D65)No ground at pin 1 (D365) -(airflow sensor) Heater element open High resistance in element P5-18 stall warning module Open circuit in wiring  Check for voltage at load side of circuit breaker Stall Warning-DC -C350 (P18). Check continuity between circuit breaker and pin 3 (D213) Check for ac voltage at load side of Stall Warning-AC circuit breaker -C351 (P18). Check continuity between circuit breaker and pin 27 (D213) Check pin 7 D213 and airplane ground Check sensor pins 1 & 2 for approx 30 ± ohms  Replace module Establish continuity Establish continuity Establish continuity Establish continuity Establish continuityEstablish continuity Replace sensor Replace module Check and correct master dim and master test circuit for stall warning system (Ref WDM 33-18-14) 
　
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