Instrument Cluster Repair

[D-O]

How sure are we that cluster failure is related to trickle chargers? I am not qualified to make that determination and I am wondering if you gents are spitballing a theory, or if you are confident this is the cause.

I had to have my cluster repaired in March, and my car spends a lot of time on a Battery Tender Plus which is probably more than twenty years old. Is it time to retire this thing and get something newer?

[D-O]

Battery Tender's take on desulfating:

https://www.batterytender.com/blogs/battery-tender-blog/why-battery-tender%C2%AE-doesn-t-use-desulfation-and-what-that-means-for-your-battery?srsltid=AfmBOooolAGcpMOT4cMMLhjbvw57ptWjo-Spua31vY8xdTPwrwQKO6uw

The whole paperclip thing seems weak, but what do I know.

[beyondm3]

Closing the loop on my fix, Scott (https://www.bmwgm5.com) fixed mine quickly and relatively inexpensive. Would recommend..

[old///MFanatic]

Closing the loop on my fix, Scott (https://www.bmwgm5.com) fixed mine quickly and relatively inexpensive. Would recommend..

Yeah Scott is legit 👍

[sapote]

My 2001 325i IKE died couple days ago even before starting the car: inserted and turned key to ON expecting to hear the gong going for couple seconds to prime the fuel before cranking, but no sound. I thought it's weird but it fired up as normal, except there was no RPM movement and other gauges were death too. Pulled fuses 10, 34, 43 to do power reset the IKE but no help. I drove it anyway using OBDFusion to monitor the coolant T. Very surprised to see it was only 68C on FWY which normally should be 92 or 93C. I thought could be the OBD craped out and not updating the Temp, so I turned on the cabin heat max to see if the coolant T drop momentary, and it dropped down couple degrees as it should. So what's going on with the very low coolant T suddenly?

I checked the wiring diagram of the IKE and the ambient T sensor signals connected to it instead of to DME as I thought. So with the death IKE which cannot tell the DME the ambient T, and the DME turned on the Tstat heater to wide open the coolant flow. I disconnected the Tstat heater and the OBD shown 93C on FWY.

Got the IKE off and had a quick look, I think the 12v to 5v DC to DC converter crapped out. Saw the darken area above the traces near the DC2DC regulator. Mine was made by Motometer, and the other supplier is Bosch.

I think most death IKE is due to the DC2DC converter circuit, and it’s not hard to find the damaged parts or traces and to fix it.

I don’t think the M3 Tstat has the controlled electric heater as in the non-M car. Any reasons?

The circled area with damaged traces:

[sapote]

This is becoming common, We need a DIY on this, I think it's the trickle charges causing the damage

On the concern of using trickle charges which can output higher voltage than the normal 14v, I don't think we should worry about it, as I checked the spec of the input DC to DC converter components and they are rated at 40v or higher, and I don't think a trickle charge over-voltage is the reason.

I think the main reason for the death IKE is the input and output electrolytic capacitors with 20 years+ stress with the high RMS current, creating internal heat, then leaking juice causing corrosion damages on the pcb traces, and the function of the caps. In a DC/DC converter, there is about 3A of AC or RMS current flowing through the caps due to PWM voltage switching -- PWM signal is 36% PWM duty to output 5v from 14v input.
All the IKE boards I have seen from internet are with Electrolytic caps which have this issue with times. Luckily the DME and transmission control modules design don't seem to have electrolytic caps (they use Tantalum caps I think) and these modules are very reliable.

[Shonky]

I highly doubt even up to 15V should kill things.

That large electrolytic cap in the circle is known to go bad and leak