VictorTL

04WDPSeDaN

iTrader: (1)

If the fuse isn't blown and the switches work, its the heating element under the leather. To replace the element, the leather needs to come off. Its typical for the bottom ones to go bad. The passenger seat only has the bottom pad as the top part of the seat is for the Airbag weight sensor.

nfnsquared

Kind of weird for low to go out on both sides...
.
Check the connections on the bottom of the switches. The "low" power wire is grey/red on the driver's side and green/yellow on the passenger side. See if those connectors came loose.

VictorTL

Acura TL Builder

losiglow

iTrader: (1)

I always found low to be reeeealy low. Like, barely noticeable. Then high was like the seat was broiling my butt. Have you noticed a difference between how low used to work and how it does (or doesn't....) now?

Acura TL Builder

VictorTL

Acura TL Builder

Acura TL Builder

VictorTL

Acura TL Builder

nfnsquared

OP, have you ever removed the switches, console or seats? Is this a flood/salvage car?

VictorTL

nfnsquared

Low and High run off the same fuse. If you have a light at the switch for either low or high, then you have power at the switch...

VictorTL

nfnsquared

Huh? Where do you see that?

VictorTL

VictorTL

redbeard1

th thermostat

br breaker

redbeard1

Hi,

From the diagram, it appears that HI adds an additional circuit to the LOW circuit. So HI is the LOW circuit plus an additional circuit. That said, while HIGH and LOW share heating elements, HI's additional circuit can power one of the two heating elements even if the LOW circuit is broken (case B). I don't think this is your problem because you would need to have breaks in two separate circuits to account for the fact you do not have heat in driver and passenger.

Another poster mentioned that it is strange both seats do not work on LOW. Usually, that means a problem upstream of both seats. My best guess is that you have some corrosion somewhere along the magenta line in "case A". This corrosion would absorb some of the heat meant for the seat. While this would also impact your seat on HI, given that HI usually is too hot, the reduction in heat for HI may not be noticed. Given that LOW is usually not too hot, the corrosion might be all that is needed to weaken LOW until the heat is not noticeable.

If you have a clamp multi-meter, you can check your amps used while you engage the LOW button. If your amps drawn increase, you can conclude you do not have a break in the circuit. In that case, the heat is being drawn, but you are not getting all of it where you want. One explanation is case A, corrosion upstream.

Jackass

Does the Driver's seatback get warm? Or just the bottom cushion? It has been a while since I have looked at electrical schematics, but I don't see anything in common between the low circuits to explain both seats losing low. But if Hi works, but Lo doesn't, that would lead me to a bad ground. I follow how this all works on the driver's seat, but not clear on the passenger's seat. Driver's seat Lo runs the two elements in series and Hi puts them in parallel. The Passenger seat looks like Lo runs through two resistors while Hi only runs through one?

Note, that Lo on my TL takes a good 10-15 minutes before I feel much heat. I normally run at Hi for about 5 minutes, the click back down to Lo after that. Even on Hi, it takes 3-4 minutes before I feel much warmth...and doesn't seem to warm anything unless someone is sitting in the seat. In my wife's Terrain, Hi lights my ass on fire within 90 seconds and will arm the seat no matter if anyone is in it.

nfnsquared

Unless I'm missing something, Hi and Low share the same ground, so I don't see how it could be a bad ground...

OP, check for voltage on the orange wire at C917 with the switch in the LOW position (may be easier said than done, not sure how easy it is to access that connector under the seat). If you have voltage, then the LOW circuit is good.

redbeard1

I'm fairly new to this electrical stuff, so apologies in advance if I misunderstood your post. I think the passenger seat and driver seat operate similarly. The only difference is the driver seat also heats an element in the back not just the bottom.

I've attached some images with how I think the electricity flows in all four cases assuming a healthy circuit.

While it is possible for the LOW light to turn on and no current reach the seat, it would be very odd if this happened in both sides. This makes me conclude the circuits are intact but damaged in some way. For example, lots of corrosion in either the positive cable (magenta in my last post) or negative cable would reduce the power in the right places in the circuit (right places being the seat). The amps are flowing but volts are being split in proportion to the resistance. This means less heat for the seat.

OP, if you don't have a clamp multi-meter, you can try the following (you may need a friend to read the meter). Put a regular multi-meter in volts mode and attach to positive and negative on the battery. Start the car. Your meter should read 14.28 or similar. While sitting in the seat, engage the LOW switch and see if your volts drop. On my car, I register a drop to 14.27 telling me the circuit is intact. The clamp meter is better as it measures amps. Using volts may not work because the draw is so small but if it does work, you know your circuit is intact and can debug with that assumption.

driver hi

driver lo

passenger lo

passenger hi

Jackass

There are two ground paths for each seat. Look at the original diagrams posted for the driver's seat. When on low, + comes in via the left side, through both heating elements, then gets ground after the seatback element on the bottom of the image. When on high, + comes in through the middle leg of the diagram, and each cushion has it's own ground. The seat back is the same ground as before, but the seat bottom gets ground via the switch.
I am still taking in the other images you uploaded to see if anything is really different. I see the diagram for the passenger seat is a tad different for sure.

Jackass

Looking at the 2nd set of diagrams posted, G601 and G602 are what I am talking about. They are in play on Lo and Hi, but on Hi there is another grounding path that will allow half the seat heat to function. This is why I was asking if the seat back is warming on the driver's seat.

nfnsquared

If G601 is bad, there won't be high or low on the driver's seat. Same thing for the passenger seat on G602.

I don't see the "other grounding path" that you are referring to for high.

I'm referencing my picture which is taken from my 04-05 Electrical Troubleshooting Manual.

Jackass

Good point...I didn't pay enough attention that both grounds are G601. I was looking at the drawn out paths without noting the label. My "other path" comment is that the electrical polarity of the Driver's seat base flips between Hi and Lo based on switch position changing where the + connection comes from and swinging the seat base to GND through the switch.

nfnsquared

Pretty sure that ground (G503) is for the indicator lights (number 3) only...

Jackass

Look at the Grey/Red line....when the switch is on Hi, it connects that leg to G503. Either way....none of our back and forth helps explain why Lo is dead on both seats.

Looking at the drawing nfnsquared posted, the Hi circuits seem to share G503...but the Lo circuits seem to have their own unique Grounds at G601 and G602. Who knows? Until the OP can get in with a meter to check a few things, we don't get much further here.

PiersD

Hi All, thanks in advance for any insights; I have a similar problem...

I'm not getting heat in either seat, both stopped working at the same time. I'm getting power as the switches light up - I even replaced the fuse anyway (strangely, the fuse in the box was a 10A whereas the fuse box and manual say it should be a 20A).

So I'm betting the relay has gone. However, where is the relay?

nfnsquared

Behind the glovebox, just to the left of the cabin air filter. There are 2 relays there, it's the left one.