E46 M3 highway shutdown: tach/speedo drop, DME unreachable afterward

[OldRanger]

How far apart are the holes on the PCB would you say?

Approximately 37mm.

[sapote]

For the capacitor, this should work and good availability, and 1000uF better than 470uF stock for better ripple filter.

https://www.mouser.com/ProductDetail/Vishay-BC-Components/MAL213817102E3?qs=cAZGeXF9iMroQhRDLdJVnA%3D%3D

The Diode is ready available https://www.digikey.com/en/products/...BoCytYQAvD_BwE

[OldRanger]

Presuming I’ve followed along accurately:

EKP Module Repair — Replacement Components

1. Power Switching IC
Infineon BTS500251TADATMA2
Digikey: 448-BTS500251TADATMA2CT-ND

2. Freewheeling Diode
Vishay VS-12CWQ04FN-M3
Digikey: VS-12CWQ04FN-M3GI-ND

3. Filter Capacitor
Vishay/BC Components MAL213817102E3 — 1000µF 40V axial
Mouser: 594-2222-138-17102

sapote — you mentioned the replacement power switching IC requires some pin reassignment. Could you clarify which pins are affected and whether that makes the repair feasible?

Also — would it be useful to create a separate reference thread consolidating the full repair guide including component identification, failure mechanism, required skills, and this parts list? Happy to do that if it adds value, or if you’d like to add or correct anything first.

[terra]

Do you have a capacitor tester? I'd be curious how that measures today. Seems like the most likely component to fail after 20 years

[OldRanger]

Do you have a capacitor tester? I'd be curious how that measures today. Seems like the most likely component to fail after 20 years

I don’t, and I’m in over my head to be honest. Would you like me to ship this one to you? I’d be happy to give it to someone that could use it to learn more about the failure, or practice this repair.

[sapote]

Presuming I’ve followed along accurately:

EKP Module Repair — Replacement Components

1. Power Switching IC
Infineon BTS500251TADATMA2
Digikey: 448-BTS500251TADATMA2CT-ND

2. Freewheeling Diode
Vishay VS-12CWQ04FN-M3
Digikey: VS-12CWQ04FN-M3GI-ND

3. Filter Capacitor
Vishay/BC Components MAL213817102E3 — 1000µF 40V axial
Mouser: 594-2222-138-17102

sapote — you mentioned the replacement power switching IC requires some pin reassignment. Could you clarify which pins are affected and whether that makes the repair feasible?

Also — would it be useful to create a separate reference thread consolidating the full repair guide including component identification, failure mechanism, required skills, and this parts list? Happy to do that if it adds value, or if you’d like to add or correct anything first.

1. For the power switch I suggest to use the BTS50080-1TMA as it's a direct pin compatible with the original part; it's will be a little warmer as the FET turned on resistance is higher but the PCB layout with copper plane will handle it just fine. I think the pump continuous current is less than 10A .
The BTS500251TADATMA2 has lower FET on resistance so it will run cooler, but it's not a direct pin for pin replacement. To use it:
* lift pin5 off the pcb and connect p5 to pin6.
* lift pin1 off the pcb and connect pin1 to GND (negative side of the big cap or any where near the chip with the same GND)
* lift pin2 off and connect it to the added N-channel signal FET (this FET to invert the input signal at pin3 before connecting to pin2 as this chip requires active high input while the original uses active low input. I will give more detail how to connect the signal FET to the circuit if we need to use this power switch).
* lift pin3 off and connect it to the pad 5 on the pcb.

3. The 20+ years old electrolytic cap, the big cap, can leak its oil out then its capacitance is reduced, leading to lower reservoir effectiveness, this leads to higher 14v ripples on the power higher side switch VBB and the high ripple voltage might exceed the max voltage spec and damaged it. The new cap with 1000uF is better in keeping the ripple voltage lower for the power switch.

To remove the parts:
* cap : cut the pins off, then melt the solder and pull the pins off the pcb
* for the dual diode and the power switch: since they are surface mounted, you have to be careful not apply to much force on the pins in the process of removing, as the force can lift the solder pads off the board. Just cut the pins off near the device and away from the pads, then melt the solder at the pad and lift the cut pin off.

[terra]

Just cut the pins off near the device and away from the pads, then melt the solder at the pad and lift the cut pin off.

This will be difficult for the large pad without preheating the board and/or using hot air.

[sapote]

This will be difficult for the large pad without preheating the board and/or using hot air.

You're right about the large heat-sink tab, and do not try to cut it off. Remove all the small pins as suggested, then heat the tab and add more solder to it to help transfer the heat from iron to the pad. This will take some time as I expect the tab heat-sink extended to the area under majority of the device. Use the largest soldering tip you can find.

[BRiley]

I just bought a new relay. If anyone has electronics skills and wants mine for testing, I'm happy to send it. Maybe we should start a Fuel EKP specific thread, so it'll be easy to find.

[sapote]

I just bought a new relay. If anyone has electronics skills and wants mine for testing, I'm happy to send it. Maybe we should start a Fuel EKP specific thread, so it'll be easy to find.

Why you needed to replace the old one?

[BRiley]

Why you needed to replace the old one?

Great question. No idea if the new one will solve my problem, but it's a start to the troubleshooting process.

[sapote]

Great question. No idea if the new one will solve my problem, but it's a start to the troubleshooting process.

What is the problem or its symptoms?

If the measured fuel pressure is about 5 bar or 72.5psi then there is no question on the pump nor the relay.

[BRiley]

What is the problem or its symptoms?

If the measured fuel pressure is about 5 bar or 72.5psi then there is no question on the pump nor the relay.

First symptom is the car started running incredibly rough when warm the other day. It turned off, and would not crank for quite some time. Once it cools down, it starts, and runs for a few. Then turns off. If I completely cool the whole car down, I can drive for a while.

The fuel pump is a few months old. Filter is also a few months old. Got the EKP tonight. Car drove fine for a while, then no start a few times. The code is a ground fault on the EKP.

Where do I go next? I checked the fuses in the DME relay, and they test fine. Ground wires look fine to me. I cleaned the contacts.

[sapote]

First symptom is the car started running incredibly rough when warm the other day. It turned off, and would not crank for quite some time. Once it cools down, it starts, and runs for a few. Then turns off. If I completely cool the whole car down, I can drive for a while.

The fuel pump is a few months old. Filter is also a few months old. Got the EKP tonight. Car drove fine for a while, then no start a few times. The code is a ground fault on the EKP.

Where do I go next? I checked the fuses in the DME relay, and they test fine. Ground wires look fine to me. I cleaned the contacts.

The error code says the relay gnd is not good. I would add a gnd wire from the relay pin7 to a good chassis GND (find a bolt or nut, or directly on the batt negative cable).

It's better to get a log file with these data when engine T reached 80C or higher: MAF in g/s, rpm, coolant temp, both fuel system status, all O2 sensors, 4 fuel trims, intake are temp. Upload the file to Datazap.me site for graphing the data, then post the site link here so we can review.

[terra]

The error code says the relay gnd is not good. I would add a gnd wire from the relay pin7 to a good chassis GND (find a bolt or nut, or directly on the batt negative cable).

Take that with a grain of salt, the DME doesn't have a good way to tell if the relay has a ground fault.