SRS Light On

Recently the red SRS (Supplementary Restraint System) light appeared on the dashboard and refused to go off. Suspecting something wrong with the airbag (because I had fiddled around with it quite a bit when taking the steering wheel off during another adventure) I connected the Star diagnosis to see what was going on. This is what I got:

Note the failure (- F -) for “06 ETR ignition circuit Front Passenger“. I had found the source of the trouble. But what was this gibberish? What the heck is an ETR ignition circuit? Something to eject the front passenger out of his seat?

Some research later, this is what I discovered: basically ETR stands for Emergency Tensioning Retractor, otherwise known as a seat belt pretensioner. When a collision is detected that is serious enough to trigger the airbag, it also triggers the seat belt pretensioner. This is essentially a mini-explosive reaction (similar to what takes place during airbag deployment) that occurs at the base of the seat belt that reels in in the seat belt, making it tighter. This ensures that you will be more safely secured to the seat during an accident. It is quite separate from the mechanism that simply prevents the seat belt from reeling out during high inertial forces.

So it appears that the circuit to trigger the pretensioner has failed. First step I need to figure out where this contraption is. After studying the MB manuals, it appears to be at the base of what is referred to as the “B-Pillar” of the car (http://en.wikipedia.org/wiki/Pillar_(automobile)) which is the pillar between the front and rear passenger window. Some dismantling later reveals this:

Note the silver cylinder. That’s where the little explosion takes place that will cause the belt strap to be reeled in. I check the resistance of this device and indeed the resistance is too low (< 1 ohm). This means the part has to be replaced. It turns out that this part cannot be replaced individually; the entire left seat belt has to be replaced at a cost of RM 1000. Ok, so easy decision – simply disable the sensor by inserting a 3 ohm resistor, and that gets rid of the annoying SRS light on the dashboard, while at the same time ensuring that I will be notified of failures in other SRS components. But for now, I can live with a non-functioning seat belt pretensioner.

Adventures in Car Repair, Part 2

Adventures in Car Repair, Part 2, a set on Flickr.

Who would have thought that so soon after my previous car problem, another would strike hardly a week later. This time it was every driver’s worst nightmare, the total breakdown. It began when I suddenly noticed that the car temperature was high, and to make matters worse I was caught in a traffic jam. I turned off all the air conditioning, and hoped for the best, although anxiety began to set in. Eventually though the temperature started to drop so I thought all was well.

I was just about to drive into the parking lot in my office when the first signs of trouble occurred. When I stepped on the gas pedal, I could hear what I can only described as “ticking” and creaking noises. Even worse, it was accompanied by a loss of power. I slowly drove into the parking lot and parked in the first available space, with a foreboding feeling that it was going to be a long night.

When I returned to the car, I checked the engine oil, and it seemed fine. I did not think to check the coolant because I thought temperature was no longer an issue, plus when I started the car the temperature seemed about normal. Thankfully, the car seemed to have returned to normal so I began the long drive home from KLCC.

About 5 minutes later, the creaking and ticking noises returned, and were even more pronounced. I put on my hazard lights and began driving very slowly. Eventually, when I got to Jalan Mahameru, and I was driving at about 10 kmh in the emergency lane, the car finally gave out completely and could no longer be started. I was still completely bewildered about what the actual problem with the car was. I had never experienced an overheating engine so I didn’t know the symptoms. Basically when the engine overheats, the fuel mixture in the cylinders starts to spontaneously combust, causing the ticking noises and causing the loss of power. Obvious only after you know.

To cut a long story short, the car was towed to a workshop to be dealt with the next morning. Early the next morning, before the workshop opened, I hooked up my Star Diagnosis System to see what on earth was going on. The system reported the car as being in perfect condition, with no faults whatsoever. Finally I checked the coolant compartment and found it bone dry. The workshop confirmed as such, and when they filled it with more water, it was obvious that the engine block had sprung a leak, as a thin stream of water was gushing out from it. I had a fleeting thought of attempting to fix it myself but realized very quickly this was way too advanced to handle.

So why did the car think all was fine, when it was clear that the cooling system had completely failed? Two reasons – the coolant level sensor had obviously failed, and the coolant temperature sensor was unreliable. Once the car was fixed, I decided to tackle the bigger problem – the coolant level sensor.

I referred to the Workshop Information Manual (WIS) software that comes with the Star Diagnosis System to determine where it was and how it works. See the pictures for the continuation of this story…

Car Repair

Car Repair, a set on Flickr.

On Awal Muharram eve, the C200 starts acting up. At low rpms it has practically no power and even if you stomp on the gas it takes a while to “catch”. The worst is when I am stopped on an incline. It will either stall or suddenly lurch forward.

I hook up my Star Diagnosis System. It says something about a problem with “unmetered air”. I unhook the air flow system and lo and behold…

Hello brave new world!

My first foray into the blogosphere!