Roll bar dash lamp - intermittent flash - PeachParts Mercedes-Benz Forum

LeaUK · #1 11-06-2005, 09:19 AM

Hi all

Here's a common one that's now just started with my '93 SL. Yesterday I noticed the dash roll bar lamp light (with a distinct flickering) then extinguish on it's own about 3 seconds later. Moving the bar up and down by 45Deg (couldn't go further as hard top is on) didn't seem to make any difference.

My model doesn't have fault code storage so I was wondering if anyone had tips where to inspect first.

First questions would be something like:

1. What causes this lamp to light

2. The flickering nature points me to simply a poor connection somewhere, recommendations on places to inspect first?

Off to review the schematics...

Cheers
Lea

LeaUK · #2 11-06-2005, 09:41 AM

I found some useful info...

Error memory
The following errors are recognized and stored in a non-volatile memory (EEPROM).

Control module defective
Voltage too low
Left belt locking relay defective
Right belt locking relay defective
Roll-over bar trigger solenoid defective
Rear axle switch short circuited to plus or ground (version up to approx. 05/95)
Malfunction indicator lamp

Version up to approx. 05/95
The stored errors can be called via pulse readout on the data link connector.

So, even though I don't have the california memory storage my roll bar module (N53) does have NVRAM. So off to build a LED flasher.

LeaUK · #3 12-09-2005, 10:13 AM

Built a basic code reader today and pulled the codes ( an illuminated momentary switch with integral 12V LED does the trick nicely).

Codes 3, 4, 5, 6 & 7.... but how long have they been there!?

So I decided to reset all codes (until only one flash is received, ie no fault) and will have to wait until the roll lamp illuminates again.

Bear with me as I'm a bit confused about reading the codes. I used pin 22 to recover the codes which according to my data is connected to the RB module but diagnostic information shows both RB + Soft Top codes together - see attachment

Codes 3,4,5,6,7 indicate soft top issues, however pin 21 connects to the soft top module!

?? Confused...

Lea

Mike Miller · #4 12-10-2005, 04:06 PM

Hi Lea,
Sorry I am not going to be much help with your questions as I am much less knowledgeable about reading codes than you are. I am quite interested in the code reader you built. I know you are very good with electronics, while I am strickly nuts and bolts. Would you care to share you simple ready diagram? I may try to build one if I have spme "Code Readers for Dummies" instructions.

LeaUK · #5 12-11-2005, 04:58 AM

Hi Mike

It's VERY simple. All you need is an illuminated momentary switch with an integral 12V LED. I used an APEM A01 (have recently been using them at work - see attached) but any illuminated momentary switch will do - see here for reference http://www.apem.co.uk/product-ranges/index.asp

To save me drawing the schematic you can find it on Jim's page right at the bottom http://pages.prodigy.net/jforgione/MB_X11.html

Of course, if you use an integral 12V LED you wont need the resistor - I didn't bother with the fuse either! If you need further info then PM me and I'll take a piccy.

Lea