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PCM question #3092429
11/07/22 09:07 PM
11/07/22 09:07 PM
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fredericksburg,va
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cudaman1969 Offline OP
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Why would my Ram Van not be going into closed loop, oxygen sensors are both working. Long term shows rich all the time, temp is 199. 12.1 mpg at any speed.

Re: PCM question [Re: cudaman1969] #3092455
11/07/22 10:16 PM
11/07/22 10:16 PM
Joined: Jan 2003
Posts: 17,920
UPPER MICHIGAN, MARQUETTE COUN...
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NITROUSN Offline
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UPPER MICHIGAN, MARQUETTE COUN...
EGR Valve.

Re: PCM question [Re: NITROUSN] #3092485
11/08/22 04:43 AM
11/08/22 04:43 AM
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fredericksburg,va
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cudaman1969 Offline OP
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I don’t think it has one in 2001?

Re: PCM question [Re: cudaman1969] #3092498
11/08/22 07:58 AM
11/08/22 07:58 AM
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N.W. Florida
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Fat_Mike Offline
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Bad ECT Sensor?

From the 2001 Service manual:



ENGINE COOLANT TEMP
SENSOR - 3.9L/5.2L/5.9L
DESCRIPTION
The Engine Coolant Temperature (ECT) sensor is
used to sense engine coolant temperature. The sensor
protrudes into an engine water jacket.
The ECT sensor is a two-wire Negative Thermal
Coefficient (NTC) sensor. Meaning, as engine coolant
temperature increases, resistance (voltage) in the
sensor decreases. As temperature decreases, resistance (voltage) in the sensor increases.
OPERATION
At key-on, the Powertrain Control Module (PCM)
sends out a regulated 5 volt signal to the ECT sensor.
The PCM then monitors the signal as it passes
through the ECT sensor to the sensor ground (sensor
return).
When the engine is cold, the PCM will operate in
Open Loop cycle. It will demand slightly richer airfuel mixtures and higher idle speeds. This is done
until normal operating temperatures are reached.
The PCM uses inputs from the ECT sensor for the
following calculations:
• for engine coolant temperature gauge operation
through CCD or PCI (J1850) communications
• Injector pulse-width
• Spark-advance curves
• ASD relay shut-down times
• Idle Air Control (IAC) motor key-on steps
• Pulse-width prime-shot during cranking
• O2 sensor closed loop times
• Purge solenoid on/off times
• EGR solenoid on/off times (if equipped)
• Leak Detection Pump operation (if equipped)
• Radiator fan relay on/off times (if equipped)
• Target idle speed
REMOVAL
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOVING THE COOLANT TEMPERATURE SENSOR.
REFER TO GROUP 7, COOLING.
(1) Partially drain cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE).
(2) Remove air cleaner assembly.
(3) Disconnect electrical connector from sensor
(Fig. 14).
(4) Engines with air conditioning: When
removing the connector from sensor, do not pull
directly on wiring harness. Fabricate an L-shaped
hook tool from a coat hanger (approximately eight
inches long). Place the hook part of tool under the
connector for removal. The connector is snapped onto
the sensor. It is not equipped with a lock type tab.
(5) Remove sensor from intake manifold.
INSTALLATION
(1) Install sensor.
(2) Tighten to 6–8 N·m (55–75 in. lbs.) torque.
(3) Connect electrical connector to sensor. The sensor connector is symmetrical (not indexed). It can be
installed to the sensor in either direction.
(4) Install air cleaner assembly.
(5) Refill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).

Re: PCM question [Re: Fat_Mike] #3092507
11/08/22 08:27 AM
11/08/22 08:27 AM
Joined: Jan 2004
Posts: 7,079
fredericksburg,va
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cudaman1969 Offline OP
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fredericksburg,va
Originally Posted by Fat_Mike
Bad ECT Sensor?

From the 2001 Service manual:



ENGINE COOLANT TEMP
SENSOR - 3.9L/5.2L/5.9L
DESCRIPTION
The Engine Coolant Temperature (ECT) sensor is
used to sense engine coolant temperature. The sensor
protrudes into an engine water jacket.
The ECT sensor is a two-wire Negative Thermal
Coefficient (NTC) sensor. Meaning, as engine coolant
temperature increases, resistance (voltage) in the
sensor decreases. As temperature decreases, resistance (voltage) in the sensor increases.
OPERATION
At key-on, the Powertrain Control Module (PCM)
sends out a regulated 5 volt signal to the ECT sensor.
The PCM then monitors the signal as it passes
through the ECT sensor to the sensor ground (sensor
return).
When the engine is cold, the PCM will operate in
Open Loop cycle. It will demand slightly richer airfuel mixtures and higher idle speeds. This is done
until normal operating temperatures are reached.
The PCM uses inputs from the ECT sensor for the
following calculations:
• for engine coolant temperature gauge operation
through CCD or PCI (J1850) communications
• Injector pulse-width
• Spark-advance curves
• ASD relay shut-down times
• Idle Air Control (IAC) motor key-on steps
• Pulse-width prime-shot during cranking
• O2 sensor closed loop times
• Purge solenoid on/off times
• EGR solenoid on/off times (if equipped)
• Leak Detection Pump operation (if equipped)
• Radiator fan relay on/off times (if equipped)
• Target idle speed
REMOVAL
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOVING THE COOLANT TEMPERATURE SENSOR.
REFER TO GROUP 7, COOLING.
(1) Partially drain cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE).
(2) Remove air cleaner assembly.
(3) Disconnect electrical connector from sensor
(Fig. 14).
(4) Engines with air conditioning: When
removing the connector from sensor, do not pull
directly on wiring harness. Fabricate an L-shaped
hook tool from a coat hanger (approximately eight
inches long). Place the hook part of tool under the
connector for removal. The connector is snapped onto
the sensor. It is not equipped with a lock type tab.
(5) Remove sensor from intake manifold.
INSTALLATION
(1) Install sensor.
(2) Tighten to 6–8 N·m (55–75 in. lbs.) torque.
(3) Connect electrical connector to sensor. The sensor connector is symmetrical (not indexed). It can be
installed to the sensor in either direction.
(4) Install air cleaner assembly.
(5) Refill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).

If bad would it still show the temp on the gauge in cluster?

Re: PCM question [Re: cudaman1969] #3092512
11/08/22 08:53 AM
11/08/22 08:53 AM
Joined: Aug 2011
Posts: 2,679
Pattison Texas
csk Offline
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Pattison Texas
I have had slow,lazy o2 sensors do that, they look good on the scanner


1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim
2020 T/A 392

Re: PCM question [Re: cudaman1969] #3092595
11/08/22 02:38 PM
11/08/22 02:38 PM
Joined: Sep 2003
Posts: 17,245
north of coder
moparx Offline
"Butt Crack Bob"
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Joined: Sep 2003
Posts: 17,245
north of coder
i think the sender for the dash gauge is a separate one.
i have seen where sender bulbs [the part that is in the coolant stream] turn "green" over time from [i think] lime deposits in the water used to top off, or refill the coolant system when changing out the mix.
those "green" deposits actually insulate the bulb from reading the exact temperature. shining the bulb back to the original brass sometimes restores the sender's function.
not saying it works 100% of the time, but it's well worth trying.
just something i have had experience with, and it's results.
your mileage will vary.
beer

Re: PCM question [Re: cudaman1969] #3092599
11/08/22 02:47 PM
11/08/22 02:47 PM
Joined: May 2003
Posts: 2,364
N.W. Florida
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Fat_Mike Offline
top fuel
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Posts: 2,364
N.W. Florida
Originally Posted by cudaman1969
If bad would it still show the temp on the gauge in cluster?


hmmm...probably not. Long story short, I was thinking realcrazy the gauge read directly from the coolant temperature sending unit. After doing more reading it looks like the gauge gets its input from the PCM, which it gets from the ECT.
I wish I had a way to send this FSM to you...

Re: PCM question [Re: Fat_Mike] #3092640
11/08/22 05:20 PM
11/08/22 05:20 PM
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Posts: 7,079
fredericksburg,va
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cudaman1969 Offline OP
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Thanks guys you’ve given me places to look. I know I have wiring issues because the trouble light and code keeps coming up TCC-overdrive, but both are working properly. No bus comes on a lot too, I beep the horn and gauges come back, no bus goes away

Re: PCM question [Re: cudaman1969] #3092642
11/08/22 05:23 PM
11/08/22 05:23 PM
Joined: Oct 2005
Posts: 4,729
WI
Dcuda69 Offline
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WI
Originally Posted by cudaman1969
Why would my Ram Van not be going into closed loop, oxygen sensors are both working. Long term shows rich all the time, temp is 199. 12.1 mpg at any speed.


Some more info might help us help you. When you say no closed loop....your scan tool shows open loop? O2 sensors working...all of them and what are the readings? Long term shows rich? What exactly is it showing and what is short term? Have all the monitors ran and passed? Any codes/pending codes? Any running concerns(besides mpg)? Have you looked at generic data in OBDII or just vehicle specific? Have you checked fuel pressure? Just some quick things that come to mind. Good luck!

Re: PCM question [Re: Dcuda69] #3092654
11/08/22 06:02 PM
11/08/22 06:02 PM
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Posts: 1,772
ILLINOIS
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volaredon Offline
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ILLINOIS
Many magnums gad 2 coolant sensors one for the gauge and one for the computer.
I'd also think hard about replacing the O2 sensors " just because" they ain't exactly new any more. Whatever you do DON'T put Bosch O2s in there mopars eat them. Use NTK, which is exactly what your van had from the factory







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