97 E300TD servo query
 

hello all
I have just bought my first ever Mercedes! A lovely E300TD AvantGarde. I see why folk swear by them! I am sure I made the right choice - I sold my new shape RangeRover to buy it and I don't regret it one bit!

I have a query for those that know about these things - I noticed that there are three cut wires leading from a round plug on the servo. these have been cut by wire cutters and the wires lead to a connector plug which enters the loom, about three inches away.

The wires are black, blue and brown and are not heavy gauge. everything appears to work fine and the lights that should light on the dashboard appear to light up and extinguish at the correct times!

Anyone got any ideas what the wires do or measure or control?

Thanks! The car is a UK spec, right hand drive automatic.

Cheers

Jim

Which servo?
Take a picture and post it with your answer!

Hi Benzmac,

Its the brake servo. thats what its called in the UK - as we are a people separated by a common language, I guess Americans might call it something else? regrettably I dont have a digital camera to take a pic.

For Brits, the brake servo is that large dinner-plate sized affair attached to the brake pedal but located in the engine compartment that amplifies braking effort by utilising vacuum from the inlet manifold or by a separate pump.

Cheers

Jim

Over here that's the brake booster.

I can only think of one reason for electrical connections to the servo - a feature known as Brake Assist (BAS). However, this feature was not introduced until the 1998 model year in the U.S. Perhaps Europe received it earlier?

BAS is a safety feature intended to help drivers better utilize the brakes during a panic stop. A computer monitors the brake pedal for very hard, aggressive braking. When the programmed threshold is exceeded BAS is activated. BAS is basically a two stage power assist for the brakes - regular and extra strength. During panic braking the servo is switched to extra strength mode. The intent is to insure drivers utilize the full braking power of the vehicle to avoid an accident. Apparently Daimler research found that typical drivers utilized only a fraction - 60% I think - of the available braking power when attempting to avoid an accident. BAS makes up the difference.

Perhaps the owners manual will verify whether your car is equipped with BAS?

I can think of only one reason why BAS may be deactivated. If one's driving style is to stab at the brakes rather than smoothly apply them, BAS can be unintentionally activated. This makes for a not very smooth driving experience. Perhaps the previous owner found it annoying?

Thanks for that.

Sorry if this sounds a bit pathetic, but I'll have to check my manual to see if I have brake assist! obviously not a big buying chioce for me, huh!!??
the car I have is a European 98 MY, and there is a ASR button on the dash/transmission tunnel. So I will have a good lookee-see as soon as I can!

Thanks for your time and trouble


Jim

I am new to this site, but there is obviously some difference in terminology in different foreign/domestic markets.

My own query shows that components have different names - for a Brit, I'd suggest that there is only one "servo" on a car - and that is the "brake booster". Similarly, here is much mention of servos on the site, which I have taken to be what I would describe as relays (??)

Is there a database where common terms are "translated" for different markets perhaps?


In international mechanical ignorance,

Jim