The bcm in my 4 speed auto has failed. I already have a bcm from a manual
Welcome to USA forum.
is your car in USA, seems not, right? where are you on the planet earth, (not ur address) a COUNTRY , matters....
we dont know what trans or engine is in your car.
so how could we guess?
why not ask suzuki this complex question, it might only need reprogramming, as is so common now.
The BCM does not shift automatics, why are you looking in there.
the TCM does that, and is part of the PCM on all modern cars.
did you scan the PCM first. that be first
to see if the TCM portion is barfing out DTC errors for the 4speed.
auto. that be first after checking fuses and connectors to trans.
and AFT levels correct, not guessing method.
Testimonial: "I am in Australia, I have solved the problem after trying the manual BCM in my auto and can say that I have found that the BCM is compatible and works perfectly in the auto.... :-)"
SOURCE: 1998 Plymouth Voyager does not shift to 3rd gear when driving,3.3
It's in limp home mode. You'll have to check wire connections and electronic controls. If it has a vacuum modulator you can remove it and look for trans fluid on the vacuum hose side (meaning ruptured diaphram). Double check the parts you replaced as well, especially if they were used parts. My dad went through three speed sensors in one year on his Caravan. You should drop the pan after checking other components. It could be a bad relay, shorted module or wire. The three speed transmissions are much more reliable than the four speed overdrive transmissions but with age and miles things can go wrong and parts will wear out.
try calling a junkyard and see if they will tell you the enterchange ok good luck
SOURCE: body control module location
the location of the bcm is at the passenger side glove box area
SOURCE: DISABLING SERVICE RIDE CONTROL via REPROGRAMMED BCM
bottom of sterring colum under under trim panel
SOURCE: Fluid capacity of a 4 speed auto in 1998 cavalier?
9.5 quarts
The check hole is located near the oil drain plug.
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The body control module (BCM)
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The powertrain control module (PCM)
With the ignition in the ON position, battery positive voltage is supplied to the automatic transmission shift lock control solenoid. The automatic transmission shift lock control solenoid receives a ground from the BCM. When the automatic transmission shift lock control solenoid is energized, the shift lever mechanically locked in the PARK position. When the driver presses the brake pedal the PCM sends a class 2 serial data message to the BCM. The BCM turns OFF the ground control circuit and this de-energizes the automatic transmission shift lock control solenoid. When the automatic transmission shift lock control solenoid is de-energized, the shift lever may be moved out of the PARK position. The BCM determines transaxle shift lever position through a class 2 serial data message from the PCM. The PCM receives inputs from the park/neutral position switch and determines shift lever position. When the BCM receives this information and determines that the shift lever is out of the PARK position, the automatic transmission shift lock control solenoid ground is opened.
1
Did you perform the A Diagnostic System Check - Automatic Transmission Shift Lock Control?
Go to Step 2
Go to Diagnostic System Check - Automatic Transmission Shift Lock Control
2
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The body control module (BCM)
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The powertrain control module (PCM) or the transmission control module (TCM).
The BCM controls the voltage to the shift lock control solenoid through the shift lock control solenoid controlled voltage circuit. The following conditions must be met before the BCM will supply voltage to the shift lock solenoid:
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The ignition is in the ON position.
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The PCM / TCM sends an input to the BCM indicating the transmission is in the PARK position.
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The BCM determines the brake pedal is not applied according the brake pedal position.
Since the shift lock control solenoid is permanently grounded, the BCM supplies voltage to the automatic transmission shift lock control solenoid, mechanically locking the shift lever in the PARK position as the solenoid energizes. When the brake pedal is applied, the BCM turns the control voltage output of the shift lock control solenoid OFF, de-energizing the shift lock control solenoid. The de-energized solenoid releases the mechanical lock allowing the driver to move the shift lever out of the PARK position. When the transmission is out of the PARK position, the shift lock control solenoid remains de-energized.
The body control module (BCM) controls the A/T shift lock control solenoid by providing battery voltage to the A/T shift lock control solenoid. The BCM utilizes a smart driver to control the voltage supplied to the A/T shift lock control solenoid. The smart driver monitors the voltage and current flow of the control circuit.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B2705 Gearshift Unlock Circuit
You could have a bad brake light switch ,
automatic transmission shift lock control solenoid.
the BCM or wiring problem
Install a scan tool. Turn ON the ignition, with the engine OFF. Press and release the brake pedal several times while observing the BTSI solenoid parameter in the body control module (BCM) output data list
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