A couple of weeks ago, the dealership had to order me a multiplex for my car because my outside trunk button stopped working. They told me that this part is in the door and it sends a signal to the latch when the button is pushed. Apparently, my multiplex is malfunctioning.
Well...now my rear passenger door won't unlock with the keyfob or when I push the unlock button on the door panel.
My question is... Does anyone know if a faulty multiplex would cause the door lock to malfunction. Or am I looking at another problem here??
Geez...I hope this isn't the beginning of a major electrical problem.

 

The TSX has a single wire in places where other cars would have multiple. This means that the single wire communicates more than one function. For instance there could be a single wire coming from the driver's bank of window switches instead of a bundle of 8 (1 for up and 1 for down of each of the 4 wires). In the setup where you have a discreet circuit for each function, the signal is transferred by simply applying voltage to the circuit. In the case of the TSX, the signal is more involved since the single wire is used to convey information about a number of different functions. In the discreet circuit design, the wire can only carry 1 bit of information, on or off. In the TSX, that wire might be able to transmit dozens of bits of information. The multiplexer is responsible for encoding (on one end of the wire) the signal from the switch into a pattern of bits so another multiplexer (on the other end) can read it and fire off the appropriate action.

It's possible that multiplexer is causing the problem with the door lock but the actual mechanical actuator that moves the lock has been a weak point in a number of other Acura models for some time. I would not be surprised to find out that the second gen TSX is still using the same failure prone part.

 

WOW!! You are a wealth of information!

I'm gonna keep my fingers crossed that it is the multiplexer cause I really don't want to have to order another part and drive an hour to the dealership to get the lock actuator replaced. Honestly...this car is starting to piss me off!

 

Isn't this a warrantee item? Or is your vehicle outside the mileage limit?

 

The actuators are pretty easy to replace yourself. You could just have it shipped to your house if need be. You could avoid the dealer gouging at the same time.

 

All of the work is warranty...my car is an 06 with 20,000 miles on it. Plus, I bought the entended warranty. I just wish I had a dealership closer to me! An hour each way really sucks!

 

That's what happens when you live amongst the hill folk.

 

Lukeatron or anyone else who knows...
Is the Multiplexer located in the driver's door? If so, where in that door exactly?

I got this part installed yesterday and my trunk and door locks are working again, but...I have developed an annoying rattle in the door and I can't seem to pinpoint where it's coming from. It's driving me insane!!

 

I do not know where it's located. The drivers door would be a logical place though with all those switches right there.

 

There are two so called "multiplex" control units in the car. One built into the master window switch and one built into the underdash fuse box. But in fact most of the control units in the car communicate thorugh the multiplex system in one of two networks.

 

Sounds more and more like the MIL-STD-1553 data bus on newer military Collins avionics systems I worked on.

 

Hmmm...in the underdash fuse box. Maybe that's where my rattle is coming from. It sounds like it's coming from the bottom of the front side of the door panel...by the door speaker. I thought it was the door panel rattling, but it's awful close to the fuse box so maybe that's what's rattling instead.
I'm about to get rid of this stupid car! Too many problems!!

 

Oooh, ooh, ooh, drive it on down here, I'd like to drive a stick for a while.

 

You've described a demux (de-multiplexer). A mux (multiplexer) has multiple inputs and a single output line. Depending on whether the signal lines are on or off, a certain input line is selected and routed to the output line (the other input lines are ignored).

If I were to "programming" the circuit, I would probably route the outside trunk button, inside trunk lever, and the fob's trunk button to an "OR" gate, and feed that into one of the mux's input lines. Basically this means that if any one of the 3 trunk triggers are active, then that input line is active. For the other mux input line, I'd just connect it to ground. The trunk switch in the glove compartment would be the mux's control/signal line (e.g., in one position, it selects the ground line, and the other connects it to the trunk triggers). So if the trunk switch is on, then whenever a trunk trigger is activated, the signal gets sent to the output line.

As for all that encoding stuff, that's more along the lines of a telecommunications multiplexer. I think it would be too expensive to use telecommunications equipment to communicate from one end of the car to the other end (nor would it be prudent, since transferring every signal at the same time would not be necessary).

It is possible to do some encoding with muxes, but you'd also have to have demuxes at the other end (along with the control signals to tell the demuxes how to de-code the signal). However, if you're going to route the control signals to the de-muxes, why not just use the control signals? A mux is useful when more than one signal feeds into a destination (e.g., device to be controlled), but only one signal can be active at a time.

 

Right right. I'm not sure what scheme the TSX is using. I know the gauge cluster is run off just a few signal wires. In that case it makes more sense to use a full mux/de-mux setup because there are so many more signals coming in. I'm not sure if all the signals are sent that way or if the tach and/or speedo have their own isolated channels. It makes plenty of sense to have all the various lights and secondary gauges run off a shared bus because their values change less frequently.

There is most definitely some sort of common bus for the windows though. Again, not sure what scheme it's using. I would guess time slicing since it's one of the simplest ways to do it. One signal wire, one timing wire, power, ground and you're set. There's only 8 bits to encode (up and down for each window) so it wouldn't even need a very high rate.

My background is definitely in telecom so that's the direction I'm looking at this from. It doesn't need to be all that complicated though.

 

Sorry to hear that. My 06, luckily, has had no problems (knock on wood) after 70,000 miles.

 

you must be the lucky one...The Wifes 06 front pass door lock is malfunctioning dang car only has 63 thousand on it...oh well

 

damn i thought i drove a lot. i have an '06 purchased at the same time as you and i have just under 40k mi.

 

Kathy is The Lucky One. Uses regular gas, has a buddy who's an SA, and no problems. She is our Reliability Poster Child.

 

Thanks-for that I might let you take a spin so you can drive a tsx with manual. My car is well taken care of by me (just ask my husband)

 

Just one correction, my buddy is a SM not a SA. He is in PA, I am in NC. The only complaints I have with this car: lousy paint-many chips, cracked foglights (replaced) but otherwise I love this car.

 

Test drove a '01 Corolla with 3-speed auto today before buying for my sweetie. Getting back into the SX was a warm bath of relief. I'd love a short-shiftin' 1/4 mile in yours sometime.

Can't we lure that SM of yours down here? My faith in AAA Automark has dropped recently.