PCM circuit/wiring questions
02-26-2006, 03:00 PM
#1
Teching In
Thread Starter
iTrader: (1)
Join Date: Dec 2005
Posts: 29
Likes: 0
Received 0 Likes
on
0 Posts
PCM circuit/wiring questions 2000 LS1/T56 combination into 1995 BMW 318ti race car.
I have the engine wiring harness unwrapped to follow all the circuits and check for insulation damage and to be able to pull unnecessary circuits.
A couple of questions:
1. The reverse inhibit solenoid. I do not have a clutch pedal position switch. What is the PCM operation here? Does the clutch switch close or open a circuit, and what does the PCM do with this data. Do I need to simply ground the clutch anticipate switch signal (B32), or do something else with the reverse inhibit solenoid control (R44)? Can I just remove the solenoid itself from the transmission and fabricate a cover? Or, is this something that can be turned off via programming of the PCM?
2. Same situation for the skip shift solenoid.
3. I found the serial data wire (B58). Is this the only wire that is used to communicate with the PCM via underdash connector?
4. Can I delete the oil level switch circuit? Does the PCM need this data to run, or can it be turned off in re-programming?
Here are some circuits I have removed from the harness. There is no A/C, cruise, emissions devices. Please advise if any are required by the PCM that can't be eliminated through re-programming.
B23 FUEL GND
B25 BANK 2 RR HO2S LO
B28 BANK 1 LR HO2S LO
B41 EGR SEN GND
B45 A/C REFRIG PRESS 5V REF
B46 5V FEED
B47 5V FEED
B55 EGR SIG
B65 BANK 2 RR HO2S HI
B68 BANK 2 LR HO2S HI
R4 AIR BYPASS VLV CTRL
R7 EGR VALVE CTRL
R13 CRUISE CTRL ENABLE SIG
R14 A/C REFRIG PRESS SEN SIG
R17 A/C REQUEST
R18 A/C CLUTCH STATUS
R30 THEFT DETER FUEL ENABLE
R34 EVAP CAN PURGE VALVE CTRL
R36 AIR PUMP RELAY CTRL
R37 CRUISE CTRL INHIBIT
R41 EGR VALVE GND
R43 A/C CLUTCH RELAY CTRL
R45 EVAP VENT VALVE CTRL
R50 VSS OUT
R53 TCS SPARK RETARD SIG
R54 FUEL LEVEL IN
I have the engine wiring harness unwrapped to follow all the circuits and check for insulation damage and to be able to pull unnecessary circuits.
A couple of questions:
1. The reverse inhibit solenoid. I do not have a clutch pedal position switch. What is the PCM operation here? Does the clutch switch close or open a circuit, and what does the PCM do with this data. Do I need to simply ground the clutch anticipate switch signal (B32), or do something else with the reverse inhibit solenoid control (R44)? Can I just remove the solenoid itself from the transmission and fabricate a cover? Or, is this something that can be turned off via programming of the PCM?
2. Same situation for the skip shift solenoid.
3. I found the serial data wire (B58). Is this the only wire that is used to communicate with the PCM via underdash connector?
4. Can I delete the oil level switch circuit? Does the PCM need this data to run, or can it be turned off in re-programming?
Here are some circuits I have removed from the harness. There is no A/C, cruise, emissions devices. Please advise if any are required by the PCM that can't be eliminated through re-programming.
B23 FUEL GND
B25 BANK 2 RR HO2S LO
B28 BANK 1 LR HO2S LO
B41 EGR SEN GND
B45 A/C REFRIG PRESS 5V REF
B46 5V FEED
B47 5V FEED
B55 EGR SIG
B65 BANK 2 RR HO2S HI
B68 BANK 2 LR HO2S HI
R4 AIR BYPASS VLV CTRL
R7 EGR VALVE CTRL
R13 CRUISE CTRL ENABLE SIG
R14 A/C REFRIG PRESS SEN SIG
R17 A/C REQUEST
R18 A/C CLUTCH STATUS
R30 THEFT DETER FUEL ENABLE
R34 EVAP CAN PURGE VALVE CTRL
R36 AIR PUMP RELAY CTRL
R37 CRUISE CTRL INHIBIT
R41 EGR VALVE GND
R43 A/C CLUTCH RELAY CTRL
R45 EVAP VENT VALVE CTRL
R50 VSS OUT
R53 TCS SPARK RETARD SIG
R54 FUEL LEVEL IN
02-28-2006, 08:20 AM
#2
The PCU uses the vss sensor signal to activate the reverse inhibit above 5 mph. No clutch position switch is necessary. I wouldn't remove it !!! Remove the connector from the skip shift solenoid and solder a 2.2 K ohm 1 watt resistor across the wires to fool the PCU.
