What gives? Is this common in all modern autos? Is it not enough solder, or a basic faulty design? Do the re-soldered units become bullet proof or are newer units being made better?
I just went through this on the fuel pump relay and now my idle is up to 1500 (89- 300e) with no adjustment possible (I think) and I hesitate to just switch out the idle control unit thinking that it may just be getting bad data.
It seems half of the common problems with these cars -climate controller, OVP, and fuel pump relay, and others I don’t know of, are all cracked solder joints!
That’s a couple hundred worth of spares that need to be added to the norm stuff I carry in the trunk!
Is there a known culprit that puts stress to the entire system?

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89 300E
79 240D
72 Westy
63 Bug sunroof
85 Jeep CJ7
86 Chevy 6.2l diesel PU

"The object of life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane."
Marcus Aurelius