Modifying a BMW E34 M5 dash (NMC9346EN chip)

juliohernandez85 · Post by **juliohernandez85** » Tue Mar 30, 2021 2:09 pm

Thanks, Antus. I managed to attach the pictures in the original post.

I am by no means an expert in programming. I do get the basics and I will get the car to a guy who specializes in car eeproms. The problem is that BMW arrived in Mexico in 1994, and since the E39 was being released in 96 they did not bring the E34, just the E36, E38 and E31. The few E34 that were brought to the country were special deliveries for a handle of wealthy businessmen.

This particular car was purchased by the owner of one of the largest banks in Mexico. He got it armored and paid over 237k USD for it

That means that the knowledge of BMW EEPROMS is almost non existent...

Let´s hope someone here has information.

mikrovega · Post by **mikrovega** » Thu Apr 08, 2021 11:40 pm

Hi,

Is the F.G. number indicated correctly and according to your car's VIN last 7 digits?

Unfortunately this is no so easy as it might be to exachange the part of coding as if you will do so, you will make the speedo to show a "dot" by the mileage at least or reject the plug.
The best proposal is to use other's car coding but in such a case F.G Number (VIN) will reflect other car (donor).

Which speedo type do You have? The one with blue rear plastic cover (with the bigger EEPROM)?

juliohernandez85 · Post by **juliohernandez85** » Fri Apr 09, 2021 2:10 pm

Hi, microvega

The VIN number showed in the Cluster test is 0000000 (same as the sticker on the coding plug). I have found other cases on the web for late models (1995)

The cluster has a blue back.

I don´t mind if I cannot input the VIN in the chip, but the most important thing is to change miles to km (changing D3 to D2 in the second row) and code the tachometer for an 8 cylinder engine, since the rpm goes way up.

Thanks for your response.

mikrovega · Post by **mikrovega** » Fri Apr 09, 2021 4:13 pm

Could be that the coding plug was replaced but it does not matter...

I would need to look for V8 E32/E34 speedo as I should have it somewhere. AFAIK it has blue back / blue coding plug and ECE (km). Typically all V8 have had automatic transmission as well.

Have you tried to modify the content on your own?

Kai and Gasplanet, mentioned in the previous messages seems to have some experience.

j_ds_au · Post by **j_ds_au** » Fri Apr 09, 2021 11:07 pm

antus wrote: 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.

In parallel ROM devices, stacking is simply a means of placing the desired data (from a smaller part) at the top of a larger part. The fact that it is the upper part of the larger device that is used, is a quirk of the way that pins are re-allocated to accommodate more address lines for larger parts.

None of that applies for a serial ROM device (since the additional address bits are sent serially over a single data pin). So in this case, the desired data is normally located at the bottom of the device, and the top of the device is unused (and might even be expected to be filled with 00 or FF).

However, the serial protocol for a larger part might have more bits than the smaller part, so the firmware that is trying to communicate with the larger-than-expected part, may not clock out sufficient bits to correctly address it (complete the serial transaction).

Joe.

juliohernandez85 · Post by **juliohernandez85** » Tue Apr 13, 2021 12:28 am

mikrovega wrote:
I would need to look for V8 E32/E34 speedo as I should have it somewhere. AFAIK it has blue back / blue coding plug and ECE (km). Typically all V8 have had automatic transmission as well.

It would be very helpful if you could share the V8 model BIN file, that way it would reduce to hit and miss modifying the Hex code.

Cheers.

mikrovega · Post by **mikrovega** » Thu May 27, 2021 7:29 pm

Hi,

Have you manage to find or modify the coding plug?

Thanks

juliohernandez85 · Post by **juliohernandez85** » Sat Jun 12, 2021 2:30 pm

mikrovega wrote:Hi,

Have you manage to find or modify the coding plug?

Thanks

Hi, Microvega. I have been very busy with work and have not been able to solve this issue. It is possible that I can get a coding plug from another e34 540 automatic or a 740 E32, but had no time to go get it at a junkyard (pre E36 models are very rare in Mexico).

Also found a guy in german forums that can send you the BIN for a fee but I have not contacted him yet.

I will keep you updated. Cheers.

mikrovega · Post by **mikrovega** » Sun Jun 13, 2021 6:23 pm

HI,

I'm also very busy.
I was able to find a speedo EU V8 Automatic.
PM me if you would also be interested in.

Cheers

juliohernandez85 · Post by **juliohernandez85** » Sun Jul 11, 2021 8:28 am

Hi to all of you.

I finally managed to recode the cluster plug. Searching trough different BMW Forums I found that there is a guy in Germany named Moritz (username EEk28) that has helped many E34/E32 owners with issues involving the C9356 EEPROM for a very reasonable fee.

I just sent him the BIN file from my car and told him my needs: miles to km on odometer, VIN on cluster test (instead of 0000000) and tachometer factor for V8. In a couple of days he sent me the data I needed so I went with an EEPROM programmer here in Mexico City and loaded the new file.

Depending on the programmer the data might need to be swapped, and I learnt it the hard way. I inserted the plug on the cluster and since the Bytes were inverted mileage went to 860148!!! (6A06 instead of 066A makes an important difference

) and the message "CODE miles/km" appeared on the central screen. also the fuel level and temperature indicators did not work and the tachometer only went to 3500rpm on full throttle.

Next day took the chip to reprogram with the bytes swapped and voilà!, everything was spot on. Mileage in kilometers, VIN on cluster test and tachometer suited for the V8 engine.

I would recommend everyone who needs help to contact Moritz. I attach pictures of the whole process , including my new BIN for those who might me interested.

Cheers.