I asked this on another forum but noone really knew.

Is there a backup system for DBW should one of the sensors fail? I would have to assume there is, or this could be a huge problem if you were pulling out into traffic (or just driving period) and all of a sudden, the gas pedal is dead.

Anyone have any info on the redundancy of this system?

 

What would you have a need for redundency? I mean, either the throttle works or it doesn't, so the car just idles. If you mean VSA redundancy, no. That's why the TSX will pop a code if something does fail and it will just turn off the system... same goes for the ABS too.

 

I mean since there is no cable connecting the gas pedal to the motor...it is all electronic... electronics can fail over time.

The whole system runs on sensors to sense the position of the gas pedal. If this sensor decides to fail in the middle of pulling out onto a busy highway, what then? I would think Acura would have a backup plan. That is what I want to know.

If VSA or ABS fails, the car still goes and the brakes still work. If DBW fails what happens?

 

I don't believe there is any kind of redundancy setup other than the ECU will switch to a "Limp mode" program should some serious emissoin device problem occured.

 

If something like that happens, the engine simply returns to idle speed due to the built-in throttle return spring. No worse than a failed alternator while driving. Just pick up the phone and call for help.

 

Ahh, in this situation, you would most likely get rear ended.

In all honesty, if your DBW fails (and I'd have to look up possible fault codes), I think you'd have bigger issues than just that "sensor"... like what computer component failed.

Ditto to what JTso said as well.

 

I guess I am just skeptical since DBW is somewhat new to cars. I have had an alternator fail on me before but it was not that drastic. It failed on the highway and I was able to limp it to the shoulder with no harm. Then I was able to replace it myself in a short amount of time.

I just think that DBW is putting alot of faith in modern technology Sure, something could fail in a regular throttle system as well, I just was curious since the whole thing is electronic.

I trust in Honda/Acura reliability... however I would never set foot in a DBW system engineered by VW with their electrical system track record. Just about everyone I know with a VW has had some kind of electrical fault within the 1st 5 years.

Thanks for the replies!

 

I'm not sure about how Honda would handle this problem should it occour. But, Being a Nissan Auto Tech (i know, i know ) I could shed some light.

I've had several DBW Nissans fail at the shop. There is a default when this occours. The check engine light was on. The idle jumps to about 1k since it no longer has a reference point for the ECU to set idle. There is a default parameter for the sensor. The vehicle's throttle was still functional, when the gas was depressed the RPM's rose slowly, and I mean slowly. So the default parameter made the car feel like it only had about 90 horses. Slugish performance.

But anyhow, the car was still driveable, but to the point where it was clearly noticed that the car had a problem.

 

Yes, but these probably weren't a fault in the DBW system itself. In fact, in 5 years of hanging out over at VWVortex, I've yet to see someone report a DBW related failure. Above all else (short of engine damage or safety-related issue), the system is designed to keep the car drivable so that you can get it off the road and to a point of service.

 

Oh no, I am not saying that there were specific VW DBW problems. Just that my inlaws and many of my friends have Passat's, GTI's, and Jetta's (even had a 92 passat myself) and all of them have had annoying problems with the electrical system. My mother in law had her 03 passat for a month and had the radio blow out 3 seperate times.

Nothing life threatening, just annoying problems that you would not expect from a company that charges as much as they do for cars and service. And it's a shame, I love the styling, espeically the GTI and the older Passat's.

I just don't trust VW/Audi like I trust Honda/Acura.

 

Ah, fair enough. Yes, there is no question that Honda's and Acura's are more reliable. VW's ruined the styling with the latest model changes IMHO, so unless the new GTI is stunning I'll probably be in a different marque, too.

 

I'm less apprehensive about Throttle by Wire than by Brake by Wire (I thought I heard they have this in some of the high end Mercedes'?)....and thankfully we haven't hit Steering by Wire yet (as far as I know in any production models???)

 

Amen. Not being able to go is one thing, But not being able to stop is another...

 

case in point, the new Prius is like that.

Braking and steering are electrical according to a Toyota Prius preview we saw in class one day. Every one of us didn't like that fact that there is no mechanical linkage to these important aspects of driving in case of a failure.

It all goes through a computer too, it's not just a direct signal either. Even the transmissions is somewhat electronically controlled.

 

Every DBW accelerator I have ever seen actually has two sensors on it. The two sensors typically operate in reverse of each other, or with some sort of voltage offset. If the ECU dectects that the relationship between the two voltages is off then it will throw a code.

I would think your chances of being hung out to dry in an intersection because of DBW is as likely as being hung out to dry in an intersection because your old, rusty accelerator cable broke!

DBW systems are typically very redundant and have numerouls fail safes built in.

Remember, this technology originated in jets (fly by wire). If it wasn't a proven technology it never would have made it in the air.

 

Fly by wire - damn Airbus!

Maybe if your throttle cuts out and your moving in cruise control range, you could kick on the cruise and hold the accelerate button! That's a last ditch effort at saving your life!

 

There are sensors in the DBW system to translate accelerator pedal position into signals to the throttle actuator control module, then finally controls the throttle plate on the throttle body via the throttle actuator. There are plenty of signal monitoring for diagnostics and the system will trigger a MIL should any problem occurs. However, the throttle body, actuator relay and the APS being electromechanical devices, there is no redundancy should these components failed. The car will most likely be disabled. The good thing is these components are generally very reliable. Should any of them failed, the diagnostic codes should provide enough information for the tech to correct the problem quickly.

 

This is very similar to having your cable snap in older systems. Either way the car goes back to idle as you cruise to the side of the road. The big difference afterwards is the cost to repair - I'd venture to guess that the actuator on a DBW car is a lot more expensive than a simple cable - although who knows, the labor might be less on the former.

In either case this not something that will come up on a new car - something to worry about after 10 years.