Modifying a BMW E39 M5 dash (NMC9346EN chip)

European GM ECUs and PCMs
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Modifying a BMW E39 M5 dash (NMC9346EN chip)

Postby antus » Thu Jul 06, 2017 11:09 am

Sorry for the semi off topic post. I know this isnt a GM, but it is a Euro vehicle so here seemed the best fit.

This chip is used in the BMW E36 M5 dashboard. Its a physical dongle which plugs in the back of the dash, and contains the dashboard calibration.

A mate of mine is trying to convert the digital display from Miles on an imported vehicle to Kms. The official BMW tools will talk to the car but dont want to talk to the dash. We dont know for sure if this is a wiring problem in the vehicle of if the dash is not supported, but suspect the dash is not supported. The usual way of modifying the calibration is to request a new code plug from BMW. They write the code plug to suit the car and its option codes and you physically plug it in to the back of the dash.

There are two versions of the IC in the code plug. The older code plugs are brown and contain a National Semiconductor NMC9346EN, which the GQ-4X is happy to read as a generic 93C46B where the B means '16 bit mode'. The brown codeplugs were replaced with blue code plugs containing a variation of the 93C56B. We did not open one of these to identify the specific chip. The GQ-4X happily reads and writes this IC as 93C56B. The BMW documentation advised the blue plugs are an update and it sounds like they can be swapped in to the older vehicles. Here is a picture of the adaptor I hacked together and the guts of the brown codeplug.

20170705_221302_resized.jpg (417.04 KiB) Viewed 171 times

The first problem is wiring the ICs. The GQ4X is failing to write the brown plug as the generic 93C46B. The bar graph jumps to 100% instantly then verification of the write fails. However it can write the blue code plug where the write bar graph takes a couple of steps before reaching 100% and then verifies correctly. As everything is the same family, I am not sure if there is a problem with specifically the 93C46B write function of the GQ-4X. Multimeter testing has shown the connections are good. Has any one attempted to write this chip with a GQ-4X?

The next part of the problem was that we wanted to move the configuration from the brown to the blue IC as that was the one we could write. Being twice the size I stacked 2 copies of the data from the brown code plug. Verification succeeds but the car rejects the code plug, and dash the dash is not correctly configured. The gauges are all wrong for example idle rpm reads at 200 rpm. Does anyone know why stacking a working brown code plug and dropping it on a blue does not work? We dont have a sample bin of the larger IC, the chip we had was a BMW spare that contained all FF and had never been programmed.

The final part of the problem is what to actually change to convert it from miles to kms. We dont have an Aussie code plug to begin with, and havnt found any tools that support this dash or bin. Does anyone have an bin our an aussie codeplug they could read and post to compare?

I'll post 2 bins. Once from the car which we are attempting to modify, and another from a spare dash with a different configuration, although still miles. If anyone is able to convert the 'car dash' file it with any tool and re-post it would be appreciated.
National Semiconductor NMC9345EN.pdf
(566.98 KiB) Downloaded 8 times
wbahd22090 bf52472 b23091 as 93c46b spare dash.bin
(128 Bytes) Downloaded 9 times
wbshd92000 ga25086 b23111 as 93c46b car dash.bin
(128 Bytes) Downloaded 9 times
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Re: Modifying a BMW E36 M5 dash (NMC9346EN chip)

Postby Tazzi » Thu Jul 06, 2017 1:09 pm

Make sure your using the latest version of the software with GQ4X, I had issues previously with an old version with writing to certain eeproms.

Bottom part of the bin looks like an odometer.. about 152045kms Id assume.. so it probably shows 94476miles on the car dash bin?

I recon maybe location 7E could be a starter.. Its just infront of the odometer so might indicate the country code?? May explain why they differ between the bins but still display miles if both places use imperial?

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