1999 DODGE RAM reset

filter the refrigerant. The orifice tube is used to meter the flow of
liquid refrigerant into the evaporator core.
HIGH PRESSURE CUT-OUT SWITCH
High pressure cut-out switch is located on compressor
discharge line, near compressor. On Dakota and Ram Pickup, it is
connected in series with the clutch cycling pressure switch and
control panel, between ground and PCM.
On Durango, it is connected in series with the electronic
cycling clutch switch, low pressure cut-out switch and control panel,
between ground and PCM. PCM controls compressor clutch operation.
On all models, when discharge pressure reaches 450-490 psi
(31.6-34.5 kg/cm
), high pressure cut-out switch interrupts A/C
request signal to PCM. PCM de-energizes compressor clutch relay,
disengaging compressor clutch. When discharge pressure drops to 270-
330 psi (23.2-19 kg/cm
) switch will close, thus restoring A/C request
signal to PCM.
HIGH PRESSURE RELIEF VALVE
High pressure relief valve is located on compressor manifold.
Valve vents system pressure if pressure is greater than 500-600 psi
(35.1-42.2 kg/cm
). Valve will reset when pressure decreases to 400
psi (28.1 kg/cm).
LOW PRESSURE CUT-OUT SWITCH OPERATION
Durango
Low pressure cut-out switch is located on suction line near
firewall. It is connected in series with the electronic cycling clutch
switch, high pressure cut-out switch and control panel, between ground
and PCM. PCM controls compressor clutch operation.
When discharge pressure reaches 10 psi (.7 kg/cm
), switch
interrupts A/C request signal to PCM. PCM de-energizes compressor
clutch relay, disengaging compressor clutch. When discharge pressure
increases to 13-27 psi (.9-1.9 kg/cm
), switch will close thus
restoring A/C request signal to PCM.
ADJUSTMENTS
TEMPERATURE CONTROL CABLE ADJUSTMENT
Dakota & Durango
1) Ensure temperature control cable housing and core are
connected at both A/C-heater control panel and A/C-heater assembly.
Ensure A/C-heater control panel is installed.
2) Rotate temperature control knob so that knob pointer is at
12 o'clock position. Pull temperature control knob straight out from
A/C-heater control panel until perimeter of knob (not knob pointer)
protrudes about .25" (6 mm) from face of A/C-heater control panel.
3) Rotate temperature control knob clockwise so that knob
pointer is at one o'clock position. Push in on knob slightly and
continue rotating knob to its full clockwise stop. Place knob pointer
at a position about .32" (8 mm) beyond end of Red stripe. Release
knob. If knob is pointing at about .32" (8 mm) beyond end of Red
stripe, go to next step. If knob is not pointing at about .32" (8 mm)
beyond end of Red stripe, go back to step 2) and repeat adjustment
procedure.
4) Rotate temperature control knob counterclockwise so that
knob pointer is at 12 o'clock position. Push temperature control knob
straight into A/C-heater control panel until perimeter of knob (not

as the malfunction is detected. A stored code indicates there was an
active code present at some time. However, the code currently may not
be present as an active code, although another active code could be.
When a trouble code occurs, the AIR BAG warning light
illuminates for 12 seconds minimum (even if problem existed for less
than 12 seconds). Code is stored, along with time in minutes it was
active, and number of times ignition has been cycled since problem was
detected.
When and if malfunction ceases to exist, an ignition cycle
count will be initiated for that code. If ignition cycle count reaches
100 without a reoccurrence of the same malfunction, DTC is erased and
that ignition cycle counter is reset to zero. If malfunction reoccurs
before count reaches 100, ignition cycle counter will be reset and DTC
will continue to be a stored code.
If a particular code is not active while performing
diagnostic test for that code, code diagnostic test may not locate the
source of the problem. In this case, stored code can only indicate an
area of system to inspect.
If no obvious problems are found, erase stored codes, and
with ignition on, wiggle wiring harness and connectors. Recheck for
codes periodically as you work through system. This procedure may
uncover a difficult problem to locate.
PRETEST INSPECTION & DIAGNOSTIC PROCEDURE
Following precautions and procedures must be followed:
* Always follow air bag service precautions to avoid air bag
deployment and possible personal injury. Refer to procedure
under See SERVICE PRECAUTIONS.
* After component replacement, ensure proper system operation.
See SYSTEM OPERATION CHECK .
* When testing voltage or continuity at ACM, use terminal side
(not wire end) of connector. DO NOT probe wire through
insulation.
* Always check if any TECH SERVICE BULLETINS (TSBs) apply to
vehicle.
* When using diagnostic charts, DO NOT skip any steps in chart
or incorrect diagnosis may result. Always perform
SYSTEM OPERATION CHECK after repairs are made.
* Always use most current DRB diagnostic program cartridge
available to prevent erroneous codes or test results.
* When using diagnostic charts, use DRB voltmeter unless
instructed to use an external voltmeter. Never use a test
light in place of a voltmeter.
* When performing electrical tests, prevent accidental
shorting of terminals. Such shorts can damage fuses or
components and may cause a second code (message) to be
set, making diagnosis of original problem more difficult.
* Vehicle must have a fully-charged battery and functional
charging system.
* Each time a connector is disconnected, inspect it to ensure
it is in good condition. Always focus on circuit being
tested. Dirt, water and corrosion, are most common problems
in connectors.
* Always disconnect DRB after use.
* Always disconnect DRB before charging battery.
USING DRB
1) Refer to DRB user guide for instructions and assistance
with reading trouble codes and other DRB functions. Under normal
operation DRB will display one of only 2 error messages: User-

* Fused B+ feed to transmission control circuit open.
* Transmission control relay defective.
* TCC solenoid control circuit open.
* TCC solenoid control circuit shorted to ground.
* TCC wire harness defective.
* Transmission control relay output circuit open.
* Transmission control relay output circuit shorted to
ground.
* PCM defective.
* Solenoid and harness assembly defective.
Diagnostic Procedure (AN & DN Bodies)
1) Using scan tool, read DTCs. If DTC P1765 is also set, go
to DTC DTC P1765: TRANS 12-VOLT SUPPLY RELAY CNTRL CIRCUIT. If DTC
P1765 is not set, go to next step.
2) Using scan tool, perform TCC SYSTEM TEST. If engine
stalls, go to next step. If engine does not stall, go to step 5).
3) Using scan tool, clear DTCs. Start engine and check for
DTCs. Wiggle wiring harness between transmission harness connector and
PCM. If DTC P0743 resets, repair wiring harness as necessary. If DTC
P0743 does not reset, go to next step.
4) Using wiring diagram as a guide, inspect wiring and
connectors. Repair wiring harness as necessary. If wiring and
connectors are okay, see INACTIVE DTC CONDITION under SELF-DIAGNOSTIC
SYSTEM. Testing is complete.
5) Turn ignition off. Disconnect transmission solenoid
harness connector. Inspect connector and terminals for damage. Repair
as necessary. If connector and terminals are okay, turn ignition on.
Using scan tool, actuate transmission control relay. Measure voltage
between ground and transmission control relay output circuit at
transmission solenoid harness connector. If voltage does not cycle
from zero to greater than 10 volts, go to step 19). If voltage cycles
from zero to greater than 10 volts, go to next step.
6) Turn ignition off. Disconnect White PCM harness connector
C2. Inspect connector and terminals for damage. Repair as necessary.
If connector and terminals are okay, turn ignition on. Measure voltage
between ground and TCC solenoid control circuit at transmission
solenoid harness connector. If voltage is greater than 10 volts, go to
next step. If voltage is 10 volts or less, go to step 8).
7) Repair TCC solenoid control circuit for short to voltage.
Reconnect PCM and transmission solenoid harness connector. Start
engine. Using scan tool, perform TCC SYSTEM TEST. If engine stalls,
testing complete. If engine does not stall, replace PCM.
8) Reconnect transmission solenoid harness connector. Remove
transmission control relay. Inspect relay connector and terminals for
damage. Repair as necessary. If connector and terminals are okay,
measure resistance between transmission control relay output circuit
at transmission control relay connector and TCC solenoid control
circuit at White PCM harness connector C2. If resistance is 40 ohms or
less, go to step 12). If resistance is greater than 40 ohms, go to
next step.
9) Reconnect transmission control relay. Measure resistance
between ground and TCC solenoid control circuit at White PCM harness
connector C2. If resistance is less than 5 ohms, repair or replace
transmission solenoid and harness assembly. If resistance is 5 ohms or
greater, go to next step.
10) Remove transmission control relay. Measure resistance
between transmission control relay output circuit at transmission
control relay connector and TCC solenoid control circuit at White PCM
harness connector C2. If resistance is 26-40 ohms, replace PCM. If
resistance is not 26-40 ohms, go to next step.
11) Turn ignition off. Disconnect transmission solenoid
harness connector. Measure resistance of TCC solenoid control circuit

15) Remove transmission control relay. Inspect connector and
terminals for damage. Repair as necessary. If connector and terminals
are okay, measure resistance of transmission control relay output
circuit between ground and transmission control relay harness
connector. If resistance is less than 5 ohms, repair short to ground
in transmission control relay output circuit. If resistance is 5 ohms
or greater, go to next step.
16) Measure resistance of transmission control relay output
circuit between transmission control relay connector and TCC solenoid
harness connector. If resistance is greater than 5 ohms, repair open
transmission control relay output circuit. If resistance is 5 ohms or
less, go to next step.
17) Turn ignition on. Measure voltage between ground and B+
circuit at transmission control relay harness connector. If voltage is
10 volts or less, repair open fused B+ circuit. If resistance is
greater than 10 volts, replace transmission control relay.
18) Record freeze frame data to determine conditions when
code was set. Using freeze frame data and wiring diagram as a guide,
inspect wiring and connectors. Repair wiring harness as necessary. If
wiring and connectors are okay, go to next step.
19) Using scan tool, clear DTCs. Start engine and check for
DTCs. Wiggle wiring harness between TCC solenoid and PCM. If DTC P0743
resets, repair wiring harness as necessary. If DTC P0743 does not
reset, see INACTIVE DTC CONDITION under SELF-DIAGNOSTIC SYSTEM.
Testing is complete.
DTC P0748: GOVERNOR PRESSURE SOL CONTROL/TRANS RELAY CIRCUITS
Circuit Description
Circuit is monitored continuously while key is on. Code sets
if voltage detected on governor pressure solenoid control circuit at
the Powertrain Control Module (PCM) does not match desired voltage for\
4.8 seconds.
Possible Causes
* Fused B+ circuit open.
* Solenoid and harness assembly defective.
* Governor pressure solenoid out of tolerance.
* Transmission control relay defective.
* Governor pressure solenoid control circuit shorted to
ground.
* Governor pressure solenoid harness defective.
* Governor pressure solenoid control circuit open.
* Transmission control relay output circuit open.
* Transmission control relay output circuit shorted to
ground.
* PCM defective.
Diagnostic Procedure (AN & DN Bodies)
1) Using scan tool, read DTCs. If DTC P1765 is set, go to DTC
DTC P1765: TRANS 12-VOLT SUPPLY RELAY CNTRL CIRCUIT. If DTC P1765 is
not set, go to next step.
2) Using scan tool, perform GOV and 3-4 SHIFT VALVE SYSTEM
TEST. Select 1st gear and read governor pressure voltage. If voltage
is one volt or greater, go to step 5). If voltage is less than one
volt, go to next step.
3) Using scan tool, erase DTCs. Start engine. Using scan
tool, read DTCs while wiggling wiring harness between governor
pressure solenoid and PCM. If DTC P0748 resets, repair wiring harness
as necessary. If DTC P0748 does not reset, go to next step.
4) Inspect all related wiring and connectors. Repair as
necessary. If wiring and connectors are okay, see INACTIVE DTC

complete.
16) Repair or replace transmission solenoid and harness
assembly. Reconnect all disconnected harness connectors. Using scan
tool, perform GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select 1st gear and
read governor pressure voltage. If voltage is one volt or greater,
replace PCM. If voltage is less than one volt, test is complete.
17) Remove transmission control relay. Inspect transmission
control relay connector and terminals for damage. Repair as necessary.
If connector and terminals are okay, turn ignition on. Measure voltage
between ground and fused B+ circuit at transmission control relay
connector. If voltage is 10 volts or less, repair open fused B+
circuit. If voltage is greater than 10 volts, go to next step.
18) Turn ignition off. Measure resistance of transmission
control relay output circuit at transmission control relay connector
and TCC solenoid harness connector. If resistance is greater than 5
ohms, repair open transmission control relay output circuit. If
resistance is 5 ohms or less, go to next step.
19) Measure resistance between ground and transmission
control relay output circuit at transmission solenoid harness
connector. If resistance is less than 5 ohms, repair short to ground
in transmission control relay output circuit. If resistance is 5 ohms
or greater, replace transmission control relay.
20) Using scan tool, erase DTCs. Start engine. Using scan
tool, read DTCs while wiggling wiring harness between governor
pressure solenoid and PCM. Note if DTC P0748 resets. If DTC P0748
resets, repair wiring harness as necessary. If DTC P0748 does not
reset, go to next step.
21) Inspect all related wiring and connectors. Repair as
necessary. If wiring and connectors are okay, see INACTIVE DTC
CONDITION under SELF-DIAGNOSTIC SYSTEM. Testing is complete.
DTC P0751: O/D SWITCH PRESSED (LO) MORE THAN 5 MIN
Circuit Description
Circuit is monitored after engine is running for 10 seconds
and reviewed every 440ms. Code sets if overdrive switch is held low
for 5 minutes or more from time of closure or ignition on.
Possible Causes
* Fused B+ circuit open.
* Solenoid and harness assembly defective.
* Governor pressure solenoid out of tolerance.
* Transmission control relay defective.
* Governor pressure solenoid control circuit shorted to
ground.
* Governor pressure solenoid harness defective.
* Governor pressure solenoid control circuit open.
* Transmission control relay output circuit open.
* Transmission control relay output circuit shorted to
ground.
* PCM defective.
Diagnostic Procedure
1) Turn ignition off. Disconnect PCM harness connectors.
Inspect connectors and terminals for damage. Repair as necessary. If
connectors and terminals are okay, measure resistance between ground
and Overdrive (O/D) off switch sense circuit at Gray PCM harness
connector C3. If resistance is less than 5 ohms, go to next step. If
resistance is 5 ohms or greater, go to step 3).
2) Disconnect O/D switch harness connector. Inspect connector
and terminals for damage. Repair as necessary. If connector and
terminals are okay, measure resistance between ground and O/D off

switch sense circuit at O/D switch harness connector. If resistance is
less than 5 ohms, repair short to ground in O/D switch sense circuit.
If resistance is 5 ohms or greater, replace O/D off switch.
3) Conditions required to set DTC P0751 are not present at
this time. DTC P0751 sets if PCM senses O/D off switch input is held
low for 5 minutes or from time of closure or ignition on. Possible
causes are: faulty O/D OFF switch, shorted wire or faulty PCM. Inspect
all related wiring and connectors. Repair as necessary. If wiring and
connectors are okay, see INACTIVE DTC CONDITION under SELF-DIAGNOSTIC
SYSTEM. Testing is complete.
DTC P0753: TRANS 3-4 SHIFT SOLENOID/TRANS RELAY CIRCUITS
Circuit Description
Circuit is monitored continuously while key is on. Code sets
if voltage detected on 3-4 shift solenoid control circuit at the
Powertrain Control Module (PCM) does not match expected voltage.
Possible Causes
* Transmission mechanically defective.
* TPS codes set.
* Transmission 3-4 solenoid wiring harness defective.
* Transmission fluid burnt or oil pan has excessive debris.
* Shift control solenoid circuit shorted to ground.
* Solenoid and harness assembly defective.
* Transmission control relay output circuit open.
* Transmission control relay output circuit shorted to
ground.
* PCM defective.
Diagnostic Procedure (AN & DN Bodies)
1) If DTC P1765 is also set, go to DTC P1765: TRANS 12-VOLT
SUPPLY RELAY CNTRL CIRCUIT. If DTC P1765 is not set, go to next step.
2) Road test vehicle and reach a speed of 50 MPH. Depress
Overdrive (OD) switch 4 times so vehicle attempts to shift from 4th
gear to 3rd gear and back. If vehicle does not shift between 3rd and
4th gear, go to step 5). If vehicle shifts between 3rd and 4th gear,
go to next step.
3) Using scan tool, erase DTCs. Start engine. Using scan
tool, read DTCs while wiggling wiring harness between 3-4 shift
solenoid and PCM. If DTC P0753 resets, repair wiring harness as
necessary. If DTC P0753 does not reset, go to next step.
4) Using wiring diagram as a guide, inspect wiring and
connectors. Repair wiring harness as necessary. If wiring and
connectors are okay, see INACTIVE DTC CONDITION under SELF-DIAGNOSTIC
SYSTEM. Testing is complete.
5) Turn ignition off. Disconnect transmission solenoid
harness connector. Turn ignition on. Using scan tool, actuate
transmission control relay. Measure voltage between ground and
transmission relay output circuit at transmission solenoid harness
connector. If voltage does not switch from zero to greater than 10
volts, go to step 16). If voltage switches from zero to greater than
10 volts, go to next step.
6) Turn ignition off. Disconnect PCM harness connectors.
Inspect connectors and terminals for damage. Repair as necessary. If
connectors and terminals are okay, turn ignition on. Measure voltage
between ground and 3-4 shift solenoid control circuit at transmission
solenoid harness connector. If voltage is greater than 10 volts, go to
next step. If voltage is 10 volts or less, go to step 8).
7) Repair 3-4 shift solenoid control circuit for short to
voltage. Reconnect all disconnected harness connectors. Road test
vehicle and reach a speed of 50 MPH. Depress Overdrive (OD) switch 4

connector. If resistance is 5 ohms or greater, repair open 3-4 shift
solenoid circuit. If resistance is less than 5 ohms, replace
transmission solenoid and harness assembly.
12) Measure resistance between transmission control relay
output circuit at transmission control relay connector and 3-4 shift
solenoid control circuit at White PCM harness connector C2. If
resistance is 26-40 ohms, replace PCM. If resistance is not 26-40
ohms, test is complete.
13) Remove transmission control relay. Inspect transmission
control relay connector and terminals for damage. Repair as necessary.
If connector and terminals are okay, turn ignition on. Measure voltage
between ground and fused B+ circuit at transmission control relay
connector. If voltage is 10 volts or less, repair open fused B+
circuit. If voltage is greater than 10 volts, go to next step.
14) Turn ignition off. Measure resistance of transmission
control relay output circuit at transmission control relay connector
and TCC solenoid harness connector. If resistance is greater than 5
ohms, repair open transmission control relay output circuit. If
resistance is 5 ohms or less, go to next step.
15) Measure resistance between ground and transmission
control relay output circuit at transmission solenoid harness
connector. If resistance is less than 5 ohms, repair short to ground
in transmission control relay output circuit. If resistance is 5 ohms
or greater, replace transmission control relay.
16) Using scan tool, erase DTCs. Start engine. Attempt to
duplicate data and reset code. Using wiring diagram as a guide,
inspect wiring and connectors. Repair wiring harness as necessary. If
wiring and connectors are okay, go to next step.
17) Wiggle wiring harness between TCC solenoid and PCM. Note
if DTC P0753 resets. If DTC P0753 resets, repair wiring harness as
necessary. If DTC P0753 does not reset, replace PCM and see INACTIVE
DTC CONDITION under SELF-DIAGNOSTIC SYSTEM. Testing is complete.
Diagnostic Procedure (WJ Body)
NOTE: If all solenoid codes, P0743, P0748 and P0753 are set, go to
test DTC P1765: TRANS 12-VOLT SUPPLY RELAY CNTRL CIRCUIT
before proceeding.
1) Using scan tool, read DTCs. If DTC SPECIFIC GOOD TRIPS
counter is not displayed or displayed count is not "0", go to next
step. If DTC SPECIFIC GOOD TRIPS counter is displayed and displayed
count is "0", go to step 16).
2) Road test vehicle and reach a speed of 50 MPH. Depress
Overdrive (OD) switch 4 times so that vehicle attempts to shift from
4th gear to 3rd gear and back. If vehicle does not shift between 3rd
and 4th gear, go to step 4). If vehicle shifts between 3rd and 4th
gear, go to next step.
3) Record freeze frame data to determine conditions when code
was set. Using wiring diagram as a guide, inspect wiring and
connectors. Repair wiring harness as necessary. If wiring and
connectors are okay, see INACTIVE DTC CONDITION under SELF-DIAGNOSTIC
SYSTEM. Testing is complete.
4) Turn ignition off. Disconnect transmission solenoid
harness connector. Inspect connector and terminals for damage. Repair
as necessary. If connector and terminals are okay, turn ignition on.
Using scan tool, actuate transmission control relay. Measure voltage
between ground and transmission relay output circuit at transmission
solenoid harness connector. If voltage does not switch from zero to
greater than 10 volts, go to step 12). If voltage switches from zero
to greater than 10 volts, go to next step.
5) Turn ignition off. Disconnect PCM harness connectors.
Inspect connectors and terminals for damage. Repair as necessary. If

connectors and terminals are okay, measure resistance between ground
and 3-4 shift solenoid control circuit at PCM harness connector. If
resistance is 5 ohms or greater, go to next step. If resistance is
less than 5 ohms, repair short to ground in 3-4 shift solenoid
circuit.
6) Measure resistance of 3-4 shift solenoid circuit between
White PCM harness connector C2 and transmission solenoid harness
connector. If resistance is 5 ohms or greater, repair open 3-4 shift
solenoid circuit. If resistance is less than 5 ohms, go to next step.
7) Turn ignition on. Measure voltage between ground and 3-4
shift solenoid control circuit at PCM harness connector. If voltage is
greater than one volt, repair 3-4 shift solenoid control circuit for
short to voltage. If voltage is one volt or less, go to next step.
8) Turn ignition off. Remove transmission control relay.
Inspect transmission control relay connector and terminals for damage.
Repair as necessary. If connector and terminals are okay, measure
resistance between transmission control relay output circuit at
transmission control relay connector and 3-4 shift solenoid control
circuit at White PCM harness connector C2. If resistance is 26-40
ohms, go to next step. If resistance is not 26-40 ohms or less,
replace 3-4 shift solenoid.
9) Measure resistance between ground and transmission control
relay output circuit at transmission control relay connector. If
resistance is less than 5 ohms, repair short to ground in transmission
control relay output circuit. If resistance is 5 ohms or greater, go
to next step.
10) Measure resistance between transmission control relay
output circuit between transmission control relay connector and
transmission solenoid harness connector. If resistance is 5 ohms or
greater, repair open transmission control relay output circuit. If
resistance is less than 5 ohms, go to next step.
11) Turn ignition on. Measure voltage between ground and
fused B+ circuit at transmission control relay connector. If voltage
is 10 volts or less, repair open fused B+ circuit. If voltage is
greater than 10 volts, replace PCM.
12) Disconnect transmission control relay. Inspect connector
and terminals for damage. Repair as necessary. If connector and
terminals are okay, turn ignition on. Replace transmission control
relay. Using scan tool, actuate transmission control relay. Measure
voltage between ground and transmission relay output circuit at
transmission solenoid harness connector. If voltage is greater than 10
volts, replace transmission control relay. If voltage is 10 volts or
less, go to next step.
13) Measure resistance of transmission control relay output
circuit between transmission control relay connector solenoid harness
connector. If resistance is 5 ohms or greater, repair open in
transmission control relay output circuit. If resistance is less than
5 ohms, go to next step.
14) Measure resistance of transmission control relay output
circuit between ground and transmission control relay connector. If
resistance is 5 ohms or greater, go to next step. If resistance is
less than 5 ohms, repair short to ground in transmission control relay
output circuit.
15) Turn ignition on. Measure voltage between ground and
fused B+ circuit at transmission control relay connector. If voltage
is 10 volts or less, repair open fused B+ circuit. If voltage is
greater than 10 volts, test is complete.
16) Using scan tool, erase DTCs. Start engine. Attempt to
duplicate data and reset code. Using wiring diagram as a guide,
inspect wiring and connectors. Repair wiring harness as necessary. If
wiring and connectors are okay, wiggle wiring harness between TCC
solenoid and PCM. Note if DTC P0753 resets. If DTC P0753 resets,
repair wiring harness as necessary. If DTC P0753 does not reset,