21
901149 REV A 12/23/10, INST 67-72 CHEV P-UP wo AC EVAP KIT PG 21 OF 24
TROUBLE SHOO
TING INFORMA
TION CONT
.
4. SYSTEM WILL NO
T TURN ON OR
RUNS INTERMITTENL
Y
WORKS WHN ENGINE IS NO
T
RUNNING
, SHUTS OFF WHEN
ENGINE IS ST
ARTED
.
(TYPICALL
Y EARL
Y GEN 4, BUT
POSSIBLE ON ALL VERSIONS)
WILL NO
T TURN ON UNDER ANY
CONDITIONS
VERIFY CONNECTIONS ON POWER LEAD
, IGNITION
LEAD
, AND BO
TH WHITE GROUND WIRES
CHECK FOR POSITIVE POWER A
T HEA
TER V
AL
VE GREEN
WIRE
. AND BL
OWER RED WIRE
. CHA
CK FOR GROUND
ON CONTROL HEAD WHITE WIRE
5. L
OSS OF MODE DOOR
FUNCTION
NO MODE CHANGE A
T ALL
PARTIAL FUNCTION OF MODE
DOORS
CHECK FOR D
AMA
GED MODE SWIT
CH OR PO
T AND
ASSOCIA
TED WIRING
TYPICALL
Y CA
USED B
Y EV
APORA
TOR HOUSING
INST
ALLED IN A BLIND IN THE VEHICLE
. BE SURE
ALL MOUNTING L
OCA
TIONS LINE UP AND DON’T
HA
VE T
O BE FORCED INT
O POSITION
.
6. BL
OWER TURNS ON AND OFF
RAPIDL
Y
BA
TTER
Y V
OL
TA
GE IS A
T LEAST
12V
.
CHECK FOR A
T LEAST 12V BETWEEN GREEN
HEA
TER V
AL
VE WIRE AND CHASSIS GROUND
.
CHECK FOR F
A
UL
TY BA
TTER
Y OR AL
TERNA
TOR
INSURE ALL SYSTEM GROUNDS AND POWER
CONNECTION ARE CLEAN AND TIGHT
.
CHARGE BA
TTER
Y
REP
AIR OR REPLA
CE
CHECK FOR D
AMA
GED SWIT
CH OR PO
T AND
ASSOCIA
TED WIRING
SYSTEM SHUTS OFF BL
OWER A
T 10V
. POOR
CONNECTIONS OR WEAK BA
TTER
Y CAN CA
USE
SHUT DOWN A
T UP T
O 11V
BA
TTER
Y V
OL
TA
GES IS LESS
THAN 12V
7. ERA
TIC FUNCTIONS OF
BL
OWER, MODE , TEMP
, ET
C.
8. WHEN THE IGNITION IS TURNED
ON
, THE BL
OWER MOMENT
ARIL
Y
COMES ON
, THEN SHUTS OFF
.
THIS IS WITH THE BL
OWER
SWIT
CH IN THE OFF POSITION
THIS IS AN INDICA
TOR THA
T THE SYSTEM HAS
BEEN RESET
. BE SURE THE RED POWER WIRE IS ON
THE BA
TTER
Y POST AND NO
T ON A SWIT
CHED
SOURCE
. ALSO
, IF THE SYSTEM IS PULLED BEL
OW
7V EVEN FOR A SPLIT SECOND
, THE SYSTEM WILL
RESET
.
RUN RED POWER WIRE DIRECTL
Y T
O BA
TTER
Y
CHECK FOR OBSTRUCTED OR BINDING MODE
DOORS
CHECK FOR D
AMA
GED STEPPER MO
TOR OR
WIRING
VERIFY PROPER METER FUNCTION B
Y CHECKING A
KNOWN GOOD BA
TTER
YS V
OL
TA
GE
.
VERIFY BA
TTER
Y V
OL
TA
GE IS GREA
TER THAN 10
V
OL
TS AND LESS THAN 16.
NOISE INTERFERENCE FROM EITHER IGNITION OR
AL
TERNA
TOR
INST
ALL CAP
A
CIT
ORS ON IGN
. COIL
, AND AL
TERNA
TOR.
ENSURE GOOD GROUND A
T ALL POINTS
. REL
OCA
TE COIL
AND ASSOCIA
TED WIRING A
W
A
Y FROM ECU AND ECU
WIRING
. CHECK FOR BURNED OR L
OOSE PL
UG WIRES
.
IGNITION NOISE (RADIA
TED OR CONDUCTED)
WILL CA
USE THE SYSTEM T
O SHUT DOWN DUE
TO HIGH V
OL
TA
GE SPIKES
. IF THIS IS SUSPECTED
,
CHECK WITH A QU
ALITY OSCILISCOPE SPIKES
GREA
TER THAN 16V WILL SHUT DOWN ECU
.
INST
ALL A RADIO CAP
A
CIT
OR A
T THE POSITIVE
POST OF THE IGNITION COIL (SEE RADIO
CAP
A
CIT
OR INST
ALLA
TION BULLETEN). A F
A
UL
TY
AL
TERNA
TOR OR WORN OUT BA
TTER
Y CAN ALSO
RESUL
T IN THIS CONDITION FOR AL
TERNA
TOR
REGULA
TOR T
O FUNCTION PROPERL
Y.
