Need a schematic for a Lexicon PCM 41

Hi Andre , I'm guessing your Caddy won't start because of your wanting to replace the neutral safety switch .Before replacing or trying to,did check for B+ voltage coming through the switch to the PCM ? There are a lot thing's that could cause your caddy not to start !
Moving the ignition switch to the CRANK position sends a 12 V signal to the PCM ignition crank request input. The PCM verifies that it has received a valid theft password from the vehicle's theft deterrent module and that the transmission is in the PARK or NEUTRAL position. The PCM then grounds the control circuit of the START 1 relay. When the START 1 relay is energized it completes the B+ voltage circuit to the starter solenoid S terminal.
There could be a anti-theft system problem , is the security light lit on the instrument cluster ? Check the start 1 relay in the under hood fuse box . Did you test for Power an control at the relay ? Find the relay an pull it out of the fuse box , look on the bottom of it . You should see four set's of numbers 30,87 an 85,86 , 87 should B+ voltage ,30 goes to the starter solenoid .If you jumped those two the engine should crank over . If the starter is good an battery cables are good etc... I'm talking about jumping where the relay plugs into , not on the relay . Pin 86 should have B+ voltage with the key on , pin 85 goes to the PCM . PCM gives a ground to pin 85 energizing the relay sending B+ voltage to the starter .
Do you know where the PCM is located ?
Transaxle Range Switch Parity Input
connector 1 blue pin 41 ,white wire

Yes you need to test first because what you call neutral safety switch is really called
Transmission Internal Mode Switch
The transmission internal mode switch (IMS) is a sliding contact switch attached to the lower control valve body, within the transmission. The manual valve link assembly then connects the IMS to the manual valve. The four inputs to the PCM from the IMS indicate which position is selected by the transmission selector lever. This information is used for engine controls as well as determining the transmission shift patterns. The input voltage level at the PCM is high (ignition voltage) when the IMS is open and low when the switch is closed to ground. The state of each input is available for display on the scan tool. The four input parameters represented are Mode A , Mode B, Mode C and Mode P (Parity).
If the PCM detects an IMS transitional state between NEUTRAL and D4 while the vehicle is in motion, then DTC P1823 sets. DTC P1823 is a type B DTC.

1994 Trooper. 3.2 Liter engine???????????
yet another endless easte regg hunt...
can you post the symptoms first.???
speedo dead, wrong, low, too high, stuck, make noise what?
does the odometer work??????? if yes, the speed dial part is bad.
or is this the back lighting dead.?
see, we cant guess any of that.

what can i say on 1994
it's not a cable DRIVEN speedo.
i answered 2 days ago same vague question.
and will now post the same photo schematic .again.
The speed is 100% electronic.
the right wire below is power 12v
the center is ground.
the left wire is PCM speed OUTPUT.
so if the PCM has no Speed input then there will be no output
(like all computes, wrong input , wrong output.
so what is that. its the VSS sensor.
the PCM can be scanned, (ecu/ecm) did you scan it.
or do the flash codes. i bet its flashing, VSS dead. right>?
the vss is located (odometer dead)
in 1 of 3 places. (depends on your unstated drive line)
2wd, 4wd, it can be on the:
tail of transmission
tail of transfer case (4wd)
or on the rear axle pig (gear carrier top)
ever to the flash codes. code 24, DTC #24? VSS dead?
posted over 100 times.
http://www.troublecodes.net/isuzu/
its no secret how to run diag jumpers. on any car made...

Have you checked alternator input and output with a meter to see if it is getting to the battery ?

Under hood,passenger side mounted on the firewall,but ...
Could be something else ,crank sensor or cam,or ign.rotor ect.
The module like 3 hundred bucks.Try this ,turn the key
on-off-on-off-on( without out hitting the starter) the check
engine light should begin to flash.
Here is a code list,may narrow down the problem.
Diagnostic Trouble Code Descriptions and service hints. Fault Code DRB Display Code Description. Service hints. 11 No Crank reference signal at PCM No Distributor reference signal detected during engine cranking. Check the circuit between the distributor and PCM. 12 Battery Disconnect Direct Battery input to PCM disconnected within last 50 ignition key-on cycles. Normal if battery has been disconnected, otherwise check battery power and ground connections. 13** No change in MAP from start to run No difference seen between the engine MAP reading and the barometric (atmospheric) pressure reading at startup. Indicates a problem with the MAP sensor vacuum system. 14** MAP sensor voltage too low or too high MAP sensor voltage output is outside the acceptable range. 15** No Vehicle speed sensor signal No signal received from the vehicle speed sensor during road load operation. 17* Engine is cold too long Engine temperature too high or too low while traveling. Check coolant level, radiator cap, temperature sensor, and thermostat. 21** O2S Stays at center O2S shorted to voltage O2 sensor does not detect rich or lean condition, or O2 sensor input voltage too high. DRB will indicate which side with dual sensors. The O2 sensor signal should fluctuate under normal conditions. 22** ECT sensor voltage too high or too low Engine Coolant temperature sensor input out of normal range. Check engine temperature sensor. 23** Intake air temp sensor voltage too high or low Intake air manifold temperature sensor is out of range. Check sensor. 24** Throttle position sensor voltage too high or low TPS sensor is out of normal range. 25** Idle air control motor circuits A short is detected in one or more of the idle air motor circuits. 27* Injector # control circuit Injector number # output driver circuit does not respond to the control signal. Check the affected circuit. 31** EVAP Solenoid Circuit Short or open in the EVAP solenoid circuit. Check for loose, broken, or shorted wire in the charcoal canister purge solenoid wiring and connectors. 32** EGR Solenoid circuit Short or open in the EGR solenoid circuit. Check for loose, broken, or shorted wire in the EGR valve wiring and connectors. Possible air fuel ratio imbalance not detected during diagnosis. 33* AC clutch relay circuit Short or open in the AC clutch circuit. 34* Speed control circuit or speed control switch always low or high An open or short in the speed control vacuum or vent circuits. Speed control switch input above or below normal range. 35 Radiator Fan low speed relay circuit Open or short in the radiator fan relay wiring. 37** Torque converter clutch solenoid CKT or Trans temp sensor too high or low Open or short in CKT wiring or connectors. Voltage out of range at transmission temperature sensor input. See NOTE #1 below 41** Generator field not switching properly Open or short in the generator (alternator) field control (regulator) circuit. This indicates a problem with the charging circuit and the fault is set when the battery voltage from the ASD relay falls below 11.75 volts. Wiring, connectors, fuses, and the ASD relay should be checked. A shorted battery cell can also trigger this fault. 42* Auto shutdown relay circuit Open or short in the ASD relay wiring or connectors. 43** Ignition coil circuit # Open or short in number # coil circuit. Indicates that the ignition coil's peak primary circuit current is not achieved with the maximum dwell time. 44* Battery temp sensor volts out of range An open or short in the engine coolant temperature sensor circuit or a problem in the PCM's battery temperature circuit. 45* Trans OD solenoid circuit Transmission OD solenoid circuit failure. Open or short in the transmission overdrive solenoid circuit. 46** Charging system voltage too high Battery voltage sense input above target charging voltage during engine operation. Computer is indicating that the battery voltage is not being regulated. 47** Charging system voltage too low Battery voltage sense input above target charging voltage during engine operation. Also, no significant change in battery voltage was detected during a test of the generator output. 51** System lean L-Idle Adap at rich limit or lean R-Idle Adap at rich limit O2 sensor signal indicates lean air/fuel ratio during engine operation. The computer ran the mixture to the rich limit of programming, but the O2 sensor still indicated a lean condition. L or R indicate left or right side O2 sensor. Fuel pressure problems can lean the mixture and set this fault. 52** System rich L-Idle Adap at lean limit or rich R-Idle Adap at lean limit O2 sensor signal indicates rich air/fuel ratio during engine operation. The computer ran the mixture to the lean limit of programming, but the O2 sensor still indicated a rich condition. L or R indicate left or right side O2 sensor. Faulty ignition components, high or low fuel pressure, or leaking injectors can set this fault. 53* Internal PCM failure or PCM SPI comm failure An internal PCM failure or PCM communications failure has been detected. 54* No cam sync signal at PCM No fuel sync (camshaft signal) detected during engine crank. No camshaft position sensor signal was received from the distributor. Problem with the distributor synchronization circuit. 55 N/A End of message code. A DTC 55 is used to end all DTC messages. This code does not show on the DRB tool and indicates a completion of the stored codes on the Malfunction Indicator Lamp (check engine lamp). 62* PCM failure SRI miles not stored Unsuccessful attempt to update Service Reminder Indicator miles in the PCM EEPROM (memory). 63* PCM Failure EEPROM write denied Unsuccessful attempt to write and EEPROM location by the PCM. Controller failure, check the PCM. This code can be set when attempting an unauthorized reprogram of the PCM. 71** Aux 5V signal voltage low The auxiliary 5 volt supply output voltage is low. The 5 volt output signal is not reaching the required voltage level. 72** Catalytic Converter efficiency failure The catalytic converter is not converting emissions in the proper ratio.

Yes you will need to remove several components in the drivers front area of the engine compartment to get at the speed sensors. You may need to remove the battery as well as the battery tray. Computers may also be in the way. The trans cooler hoses will need to be removed from the teams mission to replace the input speed sensor.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Mechanic would have checked for good input of crank and camshaft sensors and good output of spark and fuel injectors. If they saw good input but no output, that would be a sign of a fried PCM

The 3 wire Throttle Position Sensor (TPS) is mounted on the throttle body and is connected to the throttle blade.
The TPS is a 3wire variable resistor that provides the Powertrain Control Module (PCM) with an input signal (voltage) that represents the throttle blade position of the throttle body. The sensor is connected to the throttle blade shaft. As the position of the throttle blade changes, the resistance (output voltage) of the TPS changes.
The PCM supplies approximately 5 volts to the TPS. The TPS output voltage (input signal to the PCM) represents the throttle blade position. The PCM receives an input signal voltage from the TPS. This will vary in an approximate range of from .26 volts at minimum throttle opening (idle), to 4.49 volts at wide-open throttle. Along with inputs from other sensors, the PCM uses the TPS input to determine current engine operating conditions. In response to engine operating conditions, the PCM will adjust fuel injector pulse width and ignition timing.
The PCM needs to identify the actions and position of the throttle blade at all times. This information is needed to assist in performing the following calculations:

• Components & Systems
• • Auto Shut Down Relay
  • Camshaft Position Sensor
  • Components & Systems
  • Crankcase Ventilation System
  • Crankshaft Position Sensor
  • Evaporative Emission Control System
  • Heated Oxygen Sensor
  • Idle Air Control Motor
  • Intake Air Temperature Sensor
  • Intermittent Fault Tests
  • Knock Sensor
  • Manifold Absolute Pressure Sensor
  • Positive Crankcase Ventilation System
  • Throttle Position Sensor
  • Transmission Range Sensor Solenoid Assembly
  • Vehicle Speed Control

• HOME
• REPAIR INFO
• 2001 JEEP GRAND CHEROKEE 4WD 4.0L MFI 6CYL REPAIR GUIDE
• ENGINE PERFORMANCE & EMISSION CONTROLS
• COMPONENTS & SYSTEMS
• THROTTLE POSITION SENSOR

Cherokee, Grand Cherokee, 1999-2005
Throttle Position Sensor

• OPERATION
• REMOVAL & INSTALLATION

Print

Operation

The 3 wire Throttle Position Sensor (TPS) is mounted on the throttle body and is connected to the throttle blade.
The TPS is a 3wire variable resistor that provides the Powertrain Control Module (PCM) with an input signal (voltage) that represents the throttle blade position of the throttle body. The sensor is connected to the throttle blade shaft. As the position of the throttle blade changes, the resistance (output voltage) of the TPS changes.
The PCM supplies approximately 5 volts to the TPS. The TPS output voltage (input signal to the PCM) represents the throttle blade position. The PCM receives an input signal voltage from the TPS. This will vary in an approximate range of from .26 volts at minimum throttle opening (idle), to 4.49 volts at wide-open throttle. Along with inputs from other sensors, the PCM uses the TPS input to determine current engine operating conditions. In response to engine operating conditions, the PCM will adjust fuel injector pulse width and ignition timing.
The PCM needs to identify the actions and position of the throttle blade at all times. This information is needed to assist in performing the following calculations:


Ignition timing advance Fuel injection pulse-width Idle (learned value or minimum TPS) Off-idle (0.06 volt) Wide Open Throttle (WOT) open loop (2.608 volts above learned idle voltage) Deceleration fuel lean out Fuel cutoff during cranking at WOT (2.608 volts above learned idle voltage) A/C WOT cutoff (certain automatic transmissions only)

Removal & Installation

3.7L & 4.0L

1. Disconnect TPS electrical connector.
2. Remove TPS mounting screws.
3. Remove TPS.

To Install:
The TPS is mounted to the throttle body. The throttle shaft end of throttle body slides into a socket in the TPS. The TPS must be installed so that it can be rotated a few degrees. (If sensor will not rotate, install sensor with throttle shaft on other side of socket tangs). The TPS will be under slight tension when rotated.

1. Install TPS and retaining screws.
2. Tighten screws to 7 Nm (60 inch lbs.) torque.
3. Connect TPS electrical connector to TPS.
4. Manually operate throttle (by hand) to check for any TPS binding before starting engine.

4.7L

1. Remove air duct and air resonator box at throttle body.
2. Disconnect TPS electrical connector.
3. Remove two TPS mounting bolts (screws).
4. Remove TPS from throttle body.

To Install:
The throttle shaft end of throttle body slides into a socket in TPS. The TPS must be installed so that it can be rotated a few degrees. If sensor will not rotate, install sensor with throttle shaft on other side of socket tangs. The TPS will be under slight tension when rotated.

1. Install TPS and two retaining bolts.
2. Tighten bolts to 7 Nm (60 inch lbs.) torque.
3. Manually operate throttle control lever by hand to check for any binding of TPS.
4. Connect TPS electrical connector to TPS.
5. Install air duct/air box to throttle body.

Hope this helps

before 1996 they use onboard diagnosis system for jeep.

when you turn on key you need to count check engine light blinks.

here are codes taken from internet.

11* No crank reference signal detected during engine cranking.
12* Direct battery input to PCM was disconnected within the last 50 key-on cycles.
13** No difference recognized between the engine MAP reading and the barometric (atmosphereic) pressure reading at start-up
14** MAP sensor input below minimum acceptable voltage.
or
MAP sensor input above maximum acceptable voltage.
15** No vehicle distance (speed) sensor signal detected during road load conditions.
17* Engine coolant temperature remains below normal operating temperatures during vehicle travel (thermostat).
21** Neither rich nor lean condition detected from the oxygen sensor input.
or
Oxygen sensor input voltage maintained above the normal operating range.
22** Engine coolant temperature sensor input above maximum acceptable voltage.
or
Engine coolant temperature sensor input below minimum acceptable voltage.
23** Intake manifold air temperature sensor input above maximum acceptable voltage.
or
Intake manifold air temperature sensor input below minimum acceptable voltage.
24** Throttle position sensor input above maximum acceptable voltage.
or
Throttle position sensor input below minimum acceptable voltage.
25** A shorted condition detected in one or more of the idle air control motor circuits.
27* Injector #1 output driver does not respond properly to the control signal.
or
Injector #2 output driver does not respond properly to the control signal.
or
Injector #3 output driver does not respond properly to the control signal.
or
Injector #4 output driver does not respond properly to the control signal.
or
Injector #5 output driver does not respond properly to the control signal.
or
Injector #6 output driver does not respond properly to the control signal.
33* An open or shorted condition detected in the A/C clutch relay circuit.
34* An open or shorted condition detected in the speed control vacuum or vent solenoid circuits.
or
Speed control switch input below the minimum acceptable voltage.
or
Speed control switch input above the maximum acceptable voltage.
35* An open or shorted condition detected in the radiator fan relay circuit.
41* An open or shorted condition detected in the generator field control circuit.
42* An open or shorted condition detected in the auto shutdown relay circuit.
44* An open or shorted condition exists in the engine coolant temperature sensor circuit or a problem exists in the PCM's battery temperature voltage circuit.
46** Battery voltage sense input above target charging voltage during engine operation.
47** Battery voltage sense input below target charging voltage during engine operation. Also, no significant change detected in battery voltage during active test of generator output.
51** Oxygen sensor signal input indicates lean air/fuel ratio condition during engine operation.
52** Oxygen sensor signal input indicates rich air/fuel ratio condition during engine operation.
53* PCM internal fault condition detected.
54* No fuel sync (camshaft signal) detected during engine cranking.
55* Completion of diagnostic trouble code display on the malfunction indicator lamp (check engine lamp).
62* Unsuccessful attempt to update SRI (service reminder indicator) miles in the PCM EEPROM.
63* Unsuccessful attempt to write to an EEPROM location by the PCM.

* - Check engine lamp will not illuminate at all times if this code was recorded. Cycle ignition key as described and observe code flashed by check engine lamp.

** - Check engine lamp will illuminate during engine operation if this code was recorded.

PCM = Powertrain Control Module (the engine computer)
MAP = Manifold Absolute Pressure (the sensor that measures how hard the engine is sucking air through the intake manifold
EEPROM = Electrically Erasable Programmable Read Only Memory (a type of computer chip used inside the PCM)

Here is a purge valve test from autozone.com. Is this what you needed, or what else?

COMPONENT TESTING
NOTE To relieve fuel tank pressure, the filler cap must be removed before disconnecting any fuel system component.
Canister Purge Solenoid

1. Locations vary depending on model and year. Typical locations include the firewall (left or right side) and the rear of the engine near the firewall.
2. With the ignition off, unplug the connector on the EVAP solenoid.
3. Turn ignition on, measure the voltage at the ignition switch output line, voltage should be 10.0v or more. If the voltage reading is not 10.0 volts or more, repair the circuit from the ignition switch to EVAP solenoid.
4. Disconnect the negative battery cable.
5. Disconnect the PCM harness from the PCM.
6. Check the resistance of the EVAP solenoid control circuit between the PCM harness connector and the EVAP solenoid connector. Resistance should be less than 5.0 ohms; if not, repair the opening in the circuit.
7. Connect the negative battery cable.

Fig. Purge solenoid mounted on V-8 engine

Fig. Purge solenoid installation on 2.5L engine-equipped vehicles

Fig. EVAP solenoid circuits and schematic

Fig. EVAP solenoid electrical connector

there is o actual single wire carying the vehicle speed signal to the cluster. the speedometer receives a signal over what is called the can bus system. the wheel speed sensors send a signal to the antilock brake module which in turns sends a signal to the pcm. the pcm then sends a signal over the can bus system to various controllers including the cluster. you can not tap into this wires as it will effect the entire system