1999 DODGE RAM low oil pressure

Refrigerant R-12 based systems use mineral oil, while R-134a
systems use synthetic Polyalkylene Glycol (PAG) oils. Using a mineral
oil based lubricant with R-134a will result in A/C compressor failure
due to lack of proper lubrication.
Following are the most common R-134a refrigerant oils used by
most domestic vehicles:
Chrysler Corp., Eagle & Jeep
Use ND-8 PAG oil, SUN PAG 56 oil, SP-10 PAG Oil, or SP-20 PAG
oil.
Ford Motor Co.
Use YN-12B or YN-12C PAG Refrigerant Oil (specification WSH-
M1C231-B) or SP-20 PAG Oil (specification WST-M1C231-B2).
General Motors
On all models except Saturn, use PAG Refrigerant Oil (Part
No. 12345923). On Saturn, use Saturn PAG refrigerant oil.
NOTE: PAG oil absorbs moisture very rapidly, 2.3-5.6 percent by
weight as compared to a mineral oil absorption rate of .005
percent by weight.
NOTE: Use ONLY the specified oil for the appropriate system or A/C
compressor. Always check the underhood A/C specification
label or A/C compressor label before adding refrigerant oil
to A/C system.
SYSTEM SERVICE VALVES
SCHRADER-TYPE VALVES
NOTE: Although similar in construction and operation to a tire
valve, NEVER replace a Schrader-type valve with a tire
valve.
Schrader valve is similar in construction and operation to a
tire valve. See Fig. 4. When a test gauge hose is attached (hose has
built-in valve core depressor), Schrader stem is pushed inward to the
open position and allows system pressure to reach the gauge.
If test hose being used does not have a built-in core
depressor, an adapter must be used. Never attach hoses or adapters to
a Schrader valve unless it is first connected to manifold gauge set.
Fig. 4: Schrader Service Valve (Compressor Location Shown)
SPECIAL VALVE CONNECTORS
On some General Motors models, thread size on high-side

ORIFICE TUBE REPLACEMENT
CHRYSLER CORP.
Removal & Installation (Dakota)
1) Disconnect negative battery cable. Discharge A/C system,
using approved refrigerant recovery/recycling equipment. Disconnect
liquid line at condenser outlet tube. Cover open refrigerant fittings
to protect from moisture and dirt.
2) Using 2 wrenches, loosen tube fitting and separate front
half of liquid line from rear half of liquid line. Using needle nose
pliers, remove fixed orifice tube from rear half of liquid line. Note
fixed orifice tube orientation for correct installation.
3) To install, reverse removal procedure. Ensure fixed
orifice tube is positioned correctly. Evacuate, charge, and leak test
A/C system. Ensure A/C system operates properly.
NOTE: On Ram Pickup, if the fixed orifice tube is faulty or
plugged, the liquid line and orifice tube must be replaced as
an assembly.
Removal & Installation (Ram Pickup)
Disconnect negative battery cable. Discharge A/C system,
using approved refrigerant recovery/recycling equipment. Disconnect
liquid line from evaporator inlet and condenser outlet tubes. Cover
open refrigerant fittings to protect from moisture and dirt.
Disconnect liquid line retaining clips. Remove liquid line and orifice
tube. To install, reverse removal procedure. Evacuate, charge, and
leak test A/C system. Ensure A/C system operates properly.
FORD MOTOR CO.
NOTE: Replace orifice tube whenever compressor is replaced. Fixed
orifice tube is located in the condenser-to-evaporator liquid
line.
NOTE: DO NOT use pliers to remove fixed orifice tube or twist
orifice tube in liquid line. Doing so will cause plastic
orifice tube body to break inside condenser-to-evaporator
liquid line.
Fixed Orifice Tube Replacement (Except Continental, Mustang &
Villager)
1) Disconnect negative battery cable. Discharge A/C system,
using approved refrigerant recovery/recycling equipment. On Contour
and Mystique, move power steering fluid reservoir to one side without
disconnecting hoses.
2) On all models, disconnect condenser-to-evaporator
discharge (liquid) line. Remove and discard "O" rings from line. Pour
a small amount of refrigerant oil into inlet to lubricate orifice "O"
rings.
3) Insert orifice tube remover/installer into tube and turn
tool to right to engage tangs on orifice tube. See Fig. 18. Hold "T"
handle of tool and slowly tighten nut down onto discharge line to
slowly pull orifice tube out. If orifice tube breaks off when removal
is attempted, use orifice tube extractor to pull the broken section
out. See Fig. 19.
4) Ensure replacement orifice tube is fitted with "O" ring(s)\
lubricated with clean refrigerant oil. Insert tube with short end
toward evaporator, until seated. Reconnect high pressure line. On
Contour and Mystique, tighten connection to 18 ft. lbs. (24 N.m).

4) Scan tool will automatically calculate system charge.
Depending on system charge condition, corrections are made 2 ounces at
a time. Each time a correction is made, recheck readings to ensure
proper charge. For system refrigerant capacity, see REFRIGERANT OIL &
REFRIGERANT SPECIFICATIONS article.
Breeze, Cirrus, Concorde, Intrepid, LHS, Stratus & 300M
(Manifold Gauge Set Method)
1) Attach clamp-on Thermocouple (80PK-1A) to liquid line, as\
close to condenser outlet as possible. Attach manifold gauge set to
vehicle.
2) Set parking brake, and place transaxle in Park position.
Start engine and allow to idle. Set A/C controls to outside air, panel
mode, full cool, and high blower speed. Turn A/C on, and open windows.
Operate system for a few minutes to allow system to stabilize.
3) Place cardboard over front grille area, to block airflow
through part of condenser, to set A/C pressure to 260 psi (18.3
kg/cm
). This will stop cooling fans from alternating speeds and
maintain constant pressure.
4) Record temperature reading at liquid line and discharge
pressure reading on gauges. Compare readings with values in
REFRIGERANT CHARGE LEVEL table.
5) Depending on system charge condition, corrections are made
2 ounces at a time. Each time a correction is made, recheck readings
to ensure proper charge. For system refrigerant capacity, see
REFRIGERANT OIL & REFRIGERANT SPECIFICATIONS article.
REFRIGERANT CHARGE LEVEL









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Liquid Line Temp. ( 1) Discharge PressureF (C) psi (kg/cm)
40 (4.4) ........................................... 53-75 (3.7-5.3\
)
60 (15.6) ......................................... 81-104 (5.7-7.3\
)
80 (26.7) ....................................... 111-142 (7.8-10.0\
)
100 (37.8) ..................................... 156-194 (11.0-13.6\
)
120 (48.9) ..................................... 208-259 (14.6-18.2\
)
140 (60.0) ..................................... 272-331 (19.1-23.3\
)
160 (71.1) ..................................... 353-420 (24.8-29.5\
)
180 (82.2) ..................................... 447-516 (31.4-36.3\
)
( 1) - When pressure is lower than specified, system is undercharged.
When pressure is higher than specified, system is overcharged.









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All Other Models
Ensure A/C system has been checked for leaks and evacuated.
See EVACUATING A/C SYSTEM and LEAK TESTING. Charge A/C system to
specifications. For system refrigerant capacity, see REFRIGERANT OIL &
REFRIGERANT SPECIFICATIONS article.
FORD MOTOR CO.
1) If using approved Recovery/Recycling/Charging Center (023-\
00105 or 023-00150), connect to high-side and low-side service valves.
See SERVICE VALVE LOCATIONS under SYSTEM SERVICE VALVES. Operate
charging center according to manufacturer's instructions. Charge
system with specified amount of refrigerant and refrigerant oil. See
REFRIGERANT OIL & REFRIGERANT SPECIFICATIONS article. Check amount of
refrigerant oil in system before adding oil. See COMPRESSOR
REFRIGERANT OIL CHECKING article.
2) If using manifold gauge set, connect to high-side and low-
side service valves. See SERVICE VALVE LOCATIONS under SYSTEM SERVICE

Fig. 24: Electronic Leak Detector
PREPARATION FOR LEAK TESTING
Connect manifold gauge set to air conditioning system. Ensure
low-side and high-side gauge set valves are closed. Check system
pressure. It should be at least 50 psi (3.5 kg/cm
). If system is
empty, evacuate A/C system and apply 28 in. Hg of vacuum. If system
holds vacuum for 15 minutes there most likely are no leaks present. If
low, add just enough refrigerant (about 10 ounces) to bring system to
50 psi (3.5 kg/cm
).
Ensure all joints, connections, and fittings are free of oil
dirt and other contaminants. Using a refrigerant leak detector, check
all refrigerant line connections for leaks. Check condenser and
compressor seal area.
Start engine and allow to idle. Operate A/C system for about
5 minutes. Set A/C controls to outside air, and high blower speed.
Turn A/C on, and open vehicle windows. Turn engine off and wait 2-7
minutes. Refrigerant is heavier than air. Always check for leaks at
bottom of refrigerant lines and components. Refrigerant oil will leak
with refrigerant. Visually check all connections and compressor clutch
area for oil stains. If compressor shaft seal is leaking, a fresh oil
streak will normally be seen on underside of hood, above compressor
clutch.
Always perform leak testing after A/C service. Move
refrigerant leak detector slowly to check for leaks, as leaks will not

running. Code sets if transmission temperature sensor voltage is
greater than 3.76 volts for 2.2 seconds.
Possible Causes
* Transmission solenoid and wiring harness assembly
defective.
* Transmission temperature sensor wiring harness defective.
* Transmission temperature sensor ground circuit open.
* Transmission temperature signal circuit short to voltage.
* Transmission temperature sensor signal circuit open.
* PCM defective.
* Transmission pressure/temperature sensor defective.
Diagnostic Procedures
1) On AN and DN bodies, go to next step. On all except AN and
DN bodies, use scan tool to read DTCs. If DTC SPECIFIC GOOD TRIPS
counter is not displayed or displayed count is not "0", go to step
11). If DTC SPECIFIC GOOD TRIPS counter is displayed and displayed
count is "0", go to next step.
2) Turn ignition off. Disconnect PCM harness connectors.
Inspect connectors and terminals for damage. Repair as necessary. If
connectors and terminals are okay, measure voltage between ground and
transmission temperature signal circuit at White PCM harness connector
C2. If voltage is greater than one volt, go to next step. If voltage
is one volt or less, go to step 5).
3) Disconnect transmission solenoid harness connector.
Inspect connector and terminals for damage. Repair as necessary. If
connector and terminals are okay, measure voltage between ground and
transmission temperature signal circuit at transmission solenoid
harness connector. If voltage is greater than one volt, repair
transmission temperature signal circuit for short to ground. If
voltage is one volt or less, go to next step.
4) Reconnect transmission solenoid harness connector. Remove
transmission oil pan. Disconnect transmission pressure/temperature
sensor harness connector. Measure voltage between ground and
transmission temperature signal circuit at transmission
pressure/temperature sensor harness connector. If voltage is greater
than one volt, repair or replace transmission solenoid and harness
assembly. If voltage is one volt or less, replace transmission
pressure/temperature sensor.
5) Turn ignition off. Measure resistance between transmission
temperature signal circuit at White PCM harness connector C2 and
ground circuit at Black PCM harness connector C1. If resistance is
less than 550 ohms, go to DTC P0712: TRANS TEMP SENSOR VOLTAGE TOO
LOW. If resistance is 550 ohms or more, go to next step.
6) If resistance is 550-2300 ohms, go to step 10). If
resistance is greater than 2300 ohms, go to next step.
7) Disconnect transmission solenoid harness connector.
Inspect connector and terminals for damage. Repair as necessary. If
connector and terminals are okay, measure resistance of sensor ground
circuit between Black PCM harness connector C1 and transmission
solenoid harness. If resistance is 5 ohms or greater, repair open in
transmission temperature signal circuit. If resistance is less than 5
ohms, go to next step.
8) Measure resistance of transmission temperature signal
circuit between White PCM harness connector C2 and transmission
solenoid harness connector. If resistance is less than 5 ohms, go to
next step. If resistance is 5 ohms or greater, repair open
transmission temperature signal circuit.
9) Reconnect transmission solenoid harness connector. Remove
transmission oil pan. Disconnect transmission pressure/temperature
sensor harness connector. Measure resistance of sensor ground circuit

2) If any DTCs listed are present, perform appropriate
test(s). See TORQUE CONVERTOR CLUTCH (TCC) TESTS table. If no DTCs a\
re
present, go to next step.
TORQUE CONVERTOR CLUTCH (TCC) TESTS









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DTC DTC Message
P0122 (1) ................. THROTTLE POSITION SENSOR VOLTAGE TOO LOW
P0123 ( 1) ................ THROTTLE POSITION SENSOR VOLTAGE TOO HIGH
P1696 ( 1) .......................... PCM FAILURE EEPROM WRITE DENIED
P0743 ........ TORQUE CONVERTOR CLUTCH SOLENOID/TRANS RELAY CIRCUITS
( 2) ........................................................ MISFIRE
P0320 ( 1) ......................... NO CRANK REFERENCE SIGNAL AT PCM
( 1) - See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
( 2) - Perform appropriate misfire DTC test. See appropriate
SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.









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3) Check transmission fluid for proper level and for any
debris. Fill or repair transmission as necessary. If fluid level and
condition are okay, go to next step.
4) Start engine. Using scan tool, perform TCC SYSTEM TEST. If
vehicle does not stall, go to step 9). If vehicle stalls, go to next
step.
5) Using scan tool, perform GOV and 3-4 SHIFT VALVE SYSTEM
TEST. Select 4th gear. If vehicle stalls, go to next step. If vehicle
does not stall, go to step 7).
6) Turn ignition off. Replace TCC solenoid. Using scan tool,
perform GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select 4th gear. If
vehicle stalls, problem in internal. Check for blocked passage. If
vehicle does not stall, testing is complete.
7) Turn ignition off. Remove oil pump and inspect reaction
shaft, input shaft and input seal. Repair transmission as necessary.
See appropriate AUTOMATIC TRANSMISSION OVERHAUL article. If
transmission is okay, go to next step.
8) 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.
9) Turn ignition off. Connect a pressure gauge to
transmission cooler OUT port. Start engine. Using scan tool, perform
TCC SYSTEM TEST. If pressure increases when TCC is actuated, go to
next step. If pressure does not increase, repair leaks or blockage in
hydraulic circuit, or repair valve body as necessary.
10) Turn engine off. Remove oil pump and inspect reaction
shaft, input shaft and input seal. Repair transmission as necessary.
See appropriate AUTOMATIC TRANSMISSION OVERHAUL article. If
transmission is okay, there are no other potential causes remaining.
TCC is assumed to be defective. Replace torque converter.
DTC P0743: TORQUE CONV CLUTCH SOLENOID/TRANS RELAY CKT
NOTE: To test transmission temperature sensor, engine and
transmission temperature must be less than 85F (29C).
Circuit Description
Circuit is monitored continuously while key is on. Code sets
if voltage detected on Torque Converter Clutch (TCC) at the Powertrain\
Control Module (PCM) does not match desired voltage.
Possible Causes

step.
7) Turn engine off. Drain transmission fluid and remove oil
pan. Inspect oil pan for burnt oil and debris. Repair transmission as
necessary. See appropriate AUTOMATIC TRANSMISSION OVERHAUL article. If
transmission is okay, no problem is found at this time, see INACTIVE
DTC CONDITION under SELF-DIAGNOSTIC SYSTEM. Testing is complete.
8) Leave gauges connected. Replace 3-4 shift solenoid.
Replace transmission pan and fill with fluid. Start engine and allow
engine and transmission to reach normal operating temperature. Using
scan tool, select GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select 4th gear
while monitoring pressure gauges. Governor pressure should rise to
greater than 20 psi (1.4 kg/cm
) and O/D pressure should rise to
greater than 40 psi (2.8 kg/cm). If pressures are as specified, no
problem is found at this time. Testing is complete. If pressures are
not as specified, see appropriate AUTOMATIC TRANSMISSION OVERHAUL
article, paying attention to seals and clutches related to O/D clutch.
DTC P1740: TCC OR O/D SOLENOID PERFORMANCE (BR BODY - DIESEL)
Circuit Description
Torque Converter Clutch (TCC) and overdrive clutch are tested\
when Powertrain Control Module (PCM) requests TCC engagement in 3rd
gear and overdrive. Code will set if expected RPM drop is not achieved
while attempting to engage TCC and/or overdrive. Code indicates
malfunctioning torque converter or overdrive clutch.
Possible Causes
* Fluid level or quality problem.
* Transmission wiring and connector defective.
* Transmission mechanically defective.
* Low fuel level.
* Trans temperature below 32
.
* Transfer case is in low range.
* Engine RPM trouble codes set.
* Misfire trouble code set (DTCs P0300-P0306).
* Output shaft speed trouble code set.
* PTO is engaged.
* TPS codes set (DTCs P0121-P0123).
* Torque converter defective.
Diagnostic Procedures
1) Using scan tool, read DTCs. If DTC SPECIFIC GOOD TRIPS
counter is not displayed or displayed count is not "0", go to step
16). If DTC SPECIFIC GOOD TRIPS counter is displayed and displayed
count is "0", go to next step.
2) If any DTCs listed are present, perform appropriate
test(s). See TCC OR O/D SOLENOID TESTS table. If no DTCs are present,
go to next step.
TCC OR O/D SOLENOID TESTS









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DTC Message Test
CAMSHAFT POSITION SENSOR SIGNAL .......................... ( 1) P0341
P/N SWITCH STUCK IN PARK OR IN GEAR .......................... P1899
Any Throttle Position Sensor (TPS) DTC ......................... ( 1)
Any Misfire DTC ................................................ ( 1)
Any Engine RPM DTC ............................................. ( 1)
Any Output Shaft Speed Sensor DTC .............................. ( 1)
TRANS 12-VOLT SUPPLY RELAY CNTRL CIRCUIT ..................... P1765
TORQUE CONVERTOR CLUTCH SOLENOID/TRANS RELAY CIRCUITS ........ P0743
TRANS 3-4 SHIFT SOLENOID/TRANS RELAY CIRCUITS ................ P0753

(1) - See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.








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3) Ensure fuel tank is at least 1/4 full. If fuel level is
too low, correct fuel level and retest. If fuel level is okay, go to
next step.
4) Ensure transfer case is not in low range. Shift transfer
case out of low range. If transfer case is not in low range, go to
next step.
5) Ensure PTO is not engaged. Disengage PTO. If PTO is not
engaged, go to next step.
6) Ensure transmission fluid temperature is above 32
F (0C).
Warm transmission to normal operating temperature. If transmission
fluid temperature is above 32
F (0C), go to next step.
7) Turn ignition on. Using scan tool, build a custom display
with engine RPM, output shaft SPD, TCC solenoid, O/D solenoid and
throttle position. Set overdrive to off position. Road test vehicle
and reach a steady speed of 55 MPH with a minimum throttle opening
voltage of 1.15 volts for 20 seconds. Note shift patterns while
vehicle is attaining speed. If engine RPM is within 60 RPM of output
shaft speed RPM, go to next step. If engine RPM is not within 60 RPM
of output shaft speed RPM, go to step 15).
8) If output shaft speed RPM is greater than engine RPM, go
to next step. If output shaft speed RPM is equal to or less than
engine RPM, go to step 15).
9) Road test vehicle and reach a steady speed of 55 MPH and
engage overdrive. If engine RPM is 69 percent of output shaft speed,
go to step 15). If engine RPM is not 69 percent of output shaft speed,
go to next step.
10) Connect a 0-300 psi (0-21 kg/cm
) pressure gauge to
transmission Overdrive (O/D) clutch pressure test port. Connect a
second 0-300 psi (0-21 kg/cm
) pressure gauge to transmission governor
pressure test port. See appropriate AUTOMATIC TRANSMISSION OVERHAUL
article. Ensure engine and transmission are at normal operating
temperature. With an assistant, test drive vehicle. Using scan tool,
select GOV and 3-4 SHIFT VALVE SYSTEM TEST. Select 4th gear while
monitoring pressure gauge. Governor pressure should rise to greater
than 20 psi (1.4 kg/cm
) and O/D pressure should rise to greater than
40 psi (2.8 kg/cm). If pressures are as specified, go to next step.
If pressures are not as specified, go to step 13).
11) Check transmission fluid for proper level and for any
debris. Fill or repair transmission as necessary. If fluid level and
condition are okay, go to next step.
12) Drain transmission fluid and remove oil pan. If
transmission fluid is burnt or has excessive debris, repair as
necessary. If transmission fluid is okay, go to step 23).
13) Check transmission fluid for proper level and for any
debris. Fill or repair transmission as necessary. If fluid level and
condition are okay, go to next step.
14) Leave gauges connected. Replace 3-4 shift solenoid. Start
engine and allow engine and transmission to reach normal operating
temperature. Using scan tool, select GOV and 3-4 SHIFT VALVE SYSTEM
TEST. Select 4th gear while monitoring pressure gauges. Governor
pressure should rise to greater than 20 psi (1.4 kg/cm
) and O/D
pressure should rise to greater than 40 psi (2.8 kg/cm). If pressures
are as specified, testing is complete. If pressures are not as
specified, see appropriate AUTOMATIC TRANSMISSION OVERHAUL article,
paying attention to seals and clutches related to O/D clutch.
15) Check transmission fluid for proper level and for any
debris. Fill or repair transmission as necessary. If fluid level and
condition are okay, go to next step.
16) Start engine. Using scan tool, perform TCC SYSTEM TEST.