HFM Ignition Coil Driver Transistors

[marty62]

Hi Everyone. My 1994 E220 Coupe developed a misfire which was cured by changing the ECU. The wiring to the coilpacks is in good condition, so I assumed the fault was with the coil packs themselves and changed them. I'd like to try to repair the original ECU. The MB part number is 016 545 55 32, and its Bosch part number is 0 261 203 230. It is an HFM system. I'm assuming that one or both coil drivers is damaged - an easy repair if I can identify an appropriate replacement.

I've attached a photo of the circuit board of the ECU. The coil driver transistors are the two black devices standing vertically at the far edge of the board (with clips and heatsink removed for clarity). They are 5-terminal devices (which rules out the BU931 discussed in other threads on this forum). Three alternate leads are formed forwards, with the other two formed backwards. There are no manufacturer logos. The characters 008466431C can be found on the lower front face of the devices.

The pin-out of a BU931 would be compatible with the front 3 pins of the original device. However I also need to consider the rear 2 pins because they are connected and must perform some function. (Perhaps they monitor temperature or current fault conditions)?

Does anybody have any information about the 5-pin devices please (e.g. manufacturer, part number, data sheet, how to obtain)?

Thanks in advance, Martin

 

[grober]

As far as I can make out you have an ECU from a later model W202 Cclass 2.2 petrol.
ECU ENGINE CONTROLLER MERCEDES W202 C-KLASA C220 2,2 PETROL A0165455532, A 016 545 55 32, 0261203230, BOSCH 0261203230, 0 261 203 230 auto24parts

More than likely the 5pin packages are darlington transistors with built in thermal compensation diodes with external connections. exactly what Bosch used I don't know?
Sanken - datasheet pdf

http://www.alldatasheet.com/datasheet-pdf/pdf/125029/SANKEN/SAP09N.html
or might be some form of avalanche diode protection against voltage spikes--- I'm just guessing

 

[marty62]

Graeme, thanks for taking the trouble to reply. I agree that the ECU is used in both the W124 E220 and the W202 C220. I think both use the M111.960 engine.

As for the 5-pin package, it is possible that it is a predecessor of the VB027 (or similar) from ST Microelectronics. These are basically darlington transistors but with two additional pins allowing the collector current to be internally regulated and a Diagnostic output to be fed-back to the dwell and timing controller. This theory is supported by the two additional pins being connected in parallel on the two devices. However it is still a guess. I'll keep working on this as it may be useful for others in this club. Also, as an electronics engineer it would be an admission of defeat to pay somebody else a lot of money to fix this.

Martin

 

[Stratman]

....................................
Also, as an electronics engineer it would be an admission of defeat to pay somebody else a lot of money to fix this.

Martin

This. This is the crux of the matter, and I couldn't agree more

 

[grober]

Graeme, thanks for taking the trouble to reply. I agree that the ECU is used in both the W124 E220 and the W202 C220. I think both use the M111.960 engine.

As for the 5-pin package, it is possible that it is a predecessor of the VB027 (or similar) from ST Microelectronics. These are basically darlington transistors but with two additional pins allowing the collector current to be internally regulated and a Diagnostic output to be fed-back to the dwell and timing controller. This theory is supported by the two additional pins being connected in parallel on the two devices. However it is still a guess. I'll keep working on this as it may be useful for others in this club. Also, as an electronics engineer it would be an admission of defeat to pay somebody else a lot of money to fix this.

Martin

Having had a look at VB027 spec sheet you could well be correct but getting a bit beyond me I'm afraid HTTP 301 This page has been moved
One wonders if the system would still run if you simply replaced the more sophisticated 5pin units with the older BU931 transistors.
Sometimes manufacturers got stuff custom made for particular applications and its very difficult to get exact replacements.
Good luck with the research. Keep us posted if you come up with a substitute/fix.

 

[Stratman]

VB027 supplier

They say they ship to the UK. What could go wrong?

 

[marty62]

After further thought I imagine that the two additional pins provide the diagnostic information which eventually becomes fault codes for the ignition circuit (e.g. current not achieved, misfire etc.). I had thought of trying the BU931 parts. It all depends how the controller behaves with this information missing. Anyway this is all still just an educated guess on my part at the moment so more investigation is needed. I'm working away this week and also need the car back from the restorers before I can try anything. So I'll be going quiet for a while but will update the thread with any progress.

 

[technic]

Hi,

Did anyone get any info about partnumber for this component? I have the same problem myself :/

 

[lester]

Hi Everyone. My 1994 E220 Coupe developed a misfire which was cured by changing the ECU. The wiring to the coilpacks is in good condition, so I assumed the fault was with the coil packs themselves and changed them. I'd like to try to repair the original ECU. The MB part number is 016 545 55 32, and its Bosch part number is 0 261 203 230. It is an HFM system. I'm assuming that one or both coil drivers is damaged - an easy repair if I can identify an appropriate replacement.

I've attached a photo of the circuit board of the ECU. The coil driver transistors are the two black devices standing vertically at the far edge of the board (with clips and heatsink removed for clarity). They are 5-terminal devices (which rules out the BU931 discussed in other threads on this forum). Three alternate leads are formed forwards, with the other two formed backwards. There are no manufacturer logos. The characters 008466431C can be found on the lower front face of the devices.

The pin-out of a BU931 would be compatible with the front 3 pins of the original device. However I also need to consider the rear 2 pins because they are connected and must perform some function. (Perhaps they monitor temperature or current fault conditions)?

Does anybody have any information about the 5-pin devices please (e.g. manufacturer, part number, data sheet, how to obtain)?

Thanks in advance, Martin

Hi Martin,

I have exactly the same problem, did you source any transistors?

Thanks
Les.