How to check if 540i HFM is in working order?

**M3Jokster** · 09-23-2002, 11:55 AM

Guys,

well, my 540i HFM has just arrived. since my car does not have the software yet for the larger HFM, how could i check to see if the HFM is working? I was told to measure the resistance? how to do that and what is the required ohm readings?

the only thing i check was the part number on the HFM, it matches. it's a 4-wire connector. 1-702-078 and it's a Bosch HFM, etc. etc.

It's clean, the grills are in place, no cosmetic damages what so ever. just kind of dusty...since it's been sitting in a salvage yard's counter.

also what should i use to clean it up, inside/out. air compressor? water? anything ideas would be appreciated.

TIA

M3jokster

**M3Jokster** · 09-23-2002, 02:01 PM

could anyone that has a 5-series bentley manual, please scan the resistance requirements on the HFM. thanks

i only have a 3-series manual.

**RogRacer** · 09-23-2002, 04:23 PM

I think I recall hearing that the check listed in the Bentley manual was bogus and could not be trusted for the HFM. I think Brett Anderson commented on this a while ago if memory serves....

**M3Jokster** · 09-23-2002, 06:09 PM

i checked the archive.......nothing with brett and the hfm?

**RogRacer** · 09-23-2002, 07:02 PM

Sorry...I don't believe I read it in this forum....I think it was in the back of the Roundel or perhaps it was in the UUC digest. Just something I recall.

**jmciver** · 09-23-2002, 10:22 PM

This may not be easy for you, but if you have a good local BMW shop that you trust, take it by them. They should either know how to test it, or even better, have an e34 540i in the shop so they can test it in the actual car. From what I was told by some BMW mechanics I know, the HFM either works or doesn't and you would know as soon as you turn on the car. That is what I was able to do.

**mkeyboy** · 09-29-2002, 11:35 AM

Are you planning to run the HFM w/o software?

Wondering if that will cause any damage? Cause the car to run lean?

Nick

**M3Jokster** · 09-29-2002, 11:39 AM

no, i will run the HFM w/ software.......since i don't have the software yet, and i have 90 days warranty........i just want to know if the unit is in working order........they say it works........but then how do i know? It did came from a salvage yard.

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How to check if 540i HFM is in working order?

Are you planning to run the HFM w/o software?

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