1996 e300 with bad lcd display - PeachParts Mercedes-Benz Forum

turbozeke418 · #1 11-16-2014, 02:10 AM

The LCD display on the gauge cluster on my 1996 e300 went blank the other day. the back lighting still works, but no numbers, messages etc. Is it possible to just buy a used cluster from another 1996 e320 or e430 and pull out the LCD unit and put it in mine? Obviously I can, but I was wondering if it's the computer from the car itself that stores all the mileage info etc. or if its within the actual LCD panel?

97 SL320 · #2 11-16-2014, 11:00 AM

If this is like the 97 E420 / E320 W210 body, it has a 93C53 serial EEPROM on the back center of the instrument cluster PC board. This should hold the total mileage and trip mileage. The MCU might have a EEPROM area but I haven't looked yet.

I'm going to desolder the 93C53, read it, put back in cluster, reset trip , read again. Will also add miles to total and see if it changes.

The engine computer may or may not hold mileage, I'm not sure. ( It is likely to hold the VIN )

There is a failure prone ribbon cable that attaches the LCD to PC board, some Euro sellers have these cables. Toshiba makes the LCD drivers T7932 and T7933 I haven't pulled any tech sheets yet.

Your most direct route might be to get a cluster with close miles. Try car-part.com for a nation wide salvage yard inventory search.

97 SL320 · #3 11-19-2014, 08:01 PM

Tried a few things on the E420 dash.

Read the EEPROM and it only had a few bytes of info, burned that data to another chip, display was completely blank ( no miles, time or temp ).

Read the original chip on a different reader and got nearly 1K of data, put original chip back in , had original mileage but trip odo was at 000.0. Looks like my first reader isn't working properly.

It also looks like one of the MCUs has an EEPROM area to hold miles as the 93C53 data was never altered when I pulled the chip.

There are 2 MCU's on the board:

The one near the 93C53 is marked:

NEC ( maker of chip )
78012BGC739 ( this is a 78012B series MCU )
VDO E540 ( Maker of instrument cluster, E540 looks like a house # )

According to the data sheet I've found, it has 16K of mask ROM ( program built into actual chip when made not after, isn't lost when power is off, can't be changed after chip is made ) and 152 RAM ( used as the program is running, will go away if power is lost )

The second is:

ITT
CDVJ E547 ( E547 looks like a VDO house # )
G45449.001
6113 391/S

I can't find any data on this one.

For comparison, I have a 97 S430 ( dash like the same year SL ) with these chips.

EEPROM
C56M6 ( Looks to be a 93C56 )
27PB

This is close to a MCU marked:
ITT
CDJV-E575 ( E575 looks like a VDO house # )
G48654.002
6234 45/S

I can't find any data on this one.

The other MCU is
Motorola
VDO_E408 ( VDO house number )
0F74B ( I know this is the ROM MASK order # )
LZYC9621 ( this is a line and date code 1996 21 week )

I'm still trying to find out what the red LED below the speedo needle is and what happens when it rolls past 1 M miles. Also, the displayed mileage resides in the inst cluster as the two listed above have different mileages.

turbozeke418 · #4 12-14-2014, 12:40 AM

I purchased a 1997 W210 e300 cluster thinking it would work and it doesn't. I figured it would work since its basically the same car (non-turbo). When I turn the key on the lights will come on, but there isn't any glow light till after I start the car and none of the guages etc. work either. All I need is the window for mileage errors ect. Is there any way I can just switch them and have it all work? Just wishful thinking.

97 SL320 · #5 12-14-2014, 09:43 AM

It sounds like the need the version coding read from the old unit and put into the new unit. Version coding lets the hardware know what it is supposed to do.

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