Minnesota
This is a post about an experience I had that lead me to believe I had a bad voltage regulator. Maybe others can learn from my lesson.
I used a cheap Bluetooth OBD scanner to look for trouble codes set in my Z4. The scanner told me I had 16v which is too high.
I bought an aftermarket VR and installed it. Plugged in my scanner and it read 16v. I grabbed a multimeter and measured across the battery, it read 13v (perfect).
Lesson 1
Why the discrepancy? Why does my car think it has 16v? After some research I discovered that the OBD scanner doesn't actually read voltage from a car module or computer. The scanner itself has an onboard volt meter and measures volts at the OBD port. I grabbed a different OBD scanner and plugged it in ... This 2nd scanner read 13v. Damn there was nothing wrong with my original VR. Lesson learned... Use a multimeter and measure voltage at battery from now on.
Lesson 2
I decided to leave the aftermarket VR in the car as it was controlling voltage nicely. I kept the original as a spare. A week later I did some work on the ABS system and had the battery disconnected. When work was completed I connected the battery back up. The battery warning light came on in the instrument cluster. I scanned for trouble codes and the car had the following DTCs set: 281C and 281D. Which means the main computer (DME) cannot talk to a device over the Bit Serial Data (BSD) bus. On a 2003 Z4 there is only one device on the BSD network (the voltage regulator). The VR needs a Digital Signal System (DSS) interface connection used by the voltage regulator to communicate with the engine control unit (DME) via the Bit Serial Data communication network (BSD bus). I checked the specs on my aftermarket VR and it claimed it had a DSS interface. I did some research only to find out that there are many aftermarket VR that claim they have DSS wire connect but don't implement the firmware needed to make it actually communicate correctly. I installed the original VR and my DTC codes vanished. Lesson 2 learned should have bought a Bosch VR.
Hope others can learn from my mistakes.
I used a cheap Bluetooth OBD scanner to look for trouble codes set in my Z4. The scanner told me I had 16v which is too high.
I bought an aftermarket VR and installed it. Plugged in my scanner and it read 16v. I grabbed a multimeter and measured across the battery, it read 13v (perfect).
Lesson 1
Why the discrepancy? Why does my car think it has 16v? After some research I discovered that the OBD scanner doesn't actually read voltage from a car module or computer. The scanner itself has an onboard volt meter and measures volts at the OBD port. I grabbed a different OBD scanner and plugged it in ... This 2nd scanner read 13v. Damn there was nothing wrong with my original VR. Lesson learned... Use a multimeter and measure voltage at battery from now on.
Lesson 2
I decided to leave the aftermarket VR in the car as it was controlling voltage nicely. I kept the original as a spare. A week later I did some work on the ABS system and had the battery disconnected. When work was completed I connected the battery back up. The battery warning light came on in the instrument cluster. I scanned for trouble codes and the car had the following DTCs set: 281C and 281D. Which means the main computer (DME) cannot talk to a device over the Bit Serial Data (BSD) bus. On a 2003 Z4 there is only one device on the BSD network (the voltage regulator). The VR needs a Digital Signal System (DSS) interface connection used by the voltage regulator to communicate with the engine control unit (DME) via the Bit Serial Data communication network (BSD bus). I checked the specs on my aftermarket VR and it claimed it had a DSS interface. I did some research only to find out that there are many aftermarket VR that claim they have DSS wire connect but don't implement the firmware needed to make it actually communicate correctly. I installed the original VR and my DTC codes vanished. Lesson 2 learned should have bought a Bosch VR.
Hope others can learn from my mistakes.
