MSS54HP DME troubleshoot and repair (need help finding a faulty smd component)

[Samsonite79]

Hi MSS54x gurus,
I've been trying to troubleshoot and repair a mysterious problem with one of my ebay MSS54HP DME off a wrecked M3. Long story short, the Exhaust side VANOS for this DME doesn't command the 2-channel switch BTS621L1 to activate T_NWA_F (Exhaust vanos advance) basically, the DME leaves exhaust cam around 30-32* right after I start it and increase the idle. This is not an issue with one of my stock DME, so it's not a vanos solenoid issue. I also depin the two wires to the exhaust vanos solenoid while running the DME to probe the outputs, the behavior is at the faulty DME.

My question would be where does pin 3 (IN1) terminate to on the PCB, I've already replace the BTS621L1. I've probed the other smart two channel switches on the board to verify this was a good known. I'm trying to find the faulty SMD component and replace it as needed. What tools should I be using to find this faulty component, aside a oscilloscope or DVOM.

Also, I'm a noob when it comes to electronic repairs but am a automotive technician so I'm handy with some tools. Maybe a hammer would fix this DME :-)

Thank you for reading this,
-Sam

Oh for reference here is the datasheet for BTS621L

[Samsonite79]

Okay, finally found the traces leading directly to the CPU, the fault seems to be in the Motorola ZC439512VFT20... Any one have a datasheet for this CPU? Thank you!

[ricks2006]

Hi, were you able to find a schematic or something similar to that?

[sapote]

I've been trying to troubleshoot and repair a mysterious problem with one of my ebay MSS54HP DME off a wrecked M3. Long story short, the Exhaust side VANOS for this DME doesn't command the 2-channel switch BTS621L1 to activate T_NWA_F (Exhaust vanos advance) basically, the DME leaves exhaust cam around 30-32* right after I start it and increase the idle. This is not an issue with one of my stock DME, so it's not a vanos solenoid issue. I also depin the two wires to the exhaust vanos solenoid while running the DME to probe the outputs, the behavior is at the faulty DME.

My question would be where does pin 3 (IN1) terminate to on the PCB, I've already replace the BTS621L1. I've probed the other smart two channel switches on the board to verify this was a good known. I'm trying to find the faulty SMD component and replace it as needed.

I missed this thread 2 years ago, so this is late but ...
The OP wrote that it's only 1.9v at the IN1 input pin instead of 5v and so he thought the issue was caused by the MCU. Fact is 1.9v seems to be low for logic high, but 1.9v is a valid for logic high and it should turn on the output to drive the solenoid with 12v, as 1.9v is above the minimum spec of 1.7V

[Samsonite79]

Thank you for the datasheet, I gave up on it, this DME is gonna collect dust or used for spare parts.

[sapote]

Thank you for the datasheet, I gave up on it, this DME is gonna collect dust or used for spare parts.

If the Infineon power switches are driven by 1.9v from the MCU the their output should be the expected 12v to drive the solenoids, but I wonder if the MCU can turn the control signals to 0v, because 1.9v although is logic high, it indicates the MCU has the damaged outputs or the switches are damaged and loading the MCU outputs too much. If you can lift up the switches said input pins to isolate the traces, and verify that the MCU outputs are now having the full 0 to 5v swing then just replace the two switches and the board might be good again.

[Samsonite79]

If the Infineon power switches are driven by 1.9v from the MCU the their output should be the expected 12v to drive the solenoids, but I wonder if the MCU can turn the control signals to 0v, because 1.9v although is logic high, it indicates the MCU has the damaged outputs or the switches are damaged and loading the MCU outputs too much. If you can lift up the switches said input pins to isolate the traces, and verify that the MCU outputs are now having the full 0 to 5v swing then just replace the two switches and the board might be good again.

Correct the MCU wasn't turning a control signal I followed the traces, I've desoldered the old MCU half way through the process of resoldering the new MCU from ebay I gave up. So far I've already robbed this board of a few resisters and caps for other DME repairs, it's become spare parts now :-)

[sapote]

Correct the MCU wasn't turning a control signal I followed the traces, I've desoldered the old MCU half way through the process of resoldering the new MCU from ebay I gave up. So far I've already robbed this board of a few resisters and caps for other DME repairs, it's become spare parts now :-)

Did you lift up the driver input pins to isolate the two pins from the MCU output pin? Are you saying with the drivers two input pins isolated, the MCU output control pin still only at 1.9v, and did it switch between 0v and 1.9v or just stay at 1.9v DC?