griboflavin

Hello everyone, I just last week decided to purchase a 2001 e320 wagon.
I am having an issue with the heated seats that seems odd to me but I am not very familiar with these cars yet.
The heated seats worked great every I used them last week.
This morning I hit the switch for both sides and I got nothing, no lights at all.
When the key is in the on position (engine not running) the indicator lights on the seat heater switches come on and seem to be functioning.
Any way if anyone has any suggestions or has seen this before I would appreciate some input.
I checked the two fuses that are in the circuit and they are good.
Thanks,
Jerome

Plutoe

123

griboflavin

Thanks Plutoe,
I forgot to add that yes it happens for both heating stages on both passenger and driver controls.
Are there seperate modules for each seat?
I have a mechanical background, Hondas, now Heavy duty trucks and aircraft equipment.
Are you saying there is no way to really diag. this with a multi-meter?
Only a Xentry system?
Thanks again!

Plutoe

456

griboflavin

Edited my initial reply.

Plutoe

I think that without a manual your issues are in system understanding!

A system view is that for the heated seats to function the ignition switch must at least be in 1---that said there are two switches(two LED's per switch(stage 1 and 2) and one control module for the front seats. The control module controls the heat up function

There is an automatic heat reduction function when stage 2 is on initially(5min) and to conserve energy the control module will switch to stage 1

Do you have a heated seat problem??

griboflavin

Thanks for the explanation!
I understand that the ignition has to be switched on for the heat to function.
The problem I am attempting to describe is that with the engine running When pressing either drivers or passengers seat heating switch I get no response, No LED, no heat.
However, when I press the heated seat switch with ignition switch in 1 or 2 I get the LEDs on the switches.

Plutoe

Assuminig fuses checked, assuming LED's not flashing--my guess is bad seat heater control module(that module controls the on/off and amount)---now the only unknown is the control module getting voltage after the car is started????

RichM

Two questions for Plutoe.

1. Would low alternator output keep the seat heaters from working when engine is on?

2. If this were the case, would the LED on the switch flash?

Plutoe

Yes, if the control module recieves voltage data <11 or>16 the LED's will flash!!---the OP's aint flashing!!

RichM

Don't want to hijack OP, but I am having a similar situation. Both seat heaters work when key is in position2, but not when engine is running. However, the passenger switch LED flashes, drivers switch does not. I have an appointment with my Indy next week for a DAS scan. His first thought was alternator, but need to scan to isolate the problem.

griboflavin

Thanks, I will be bringing my meter home this weekend and hopefully getting somewhere with it.
Thanks for the tips I will post what I find!

griboflavin

I will be checking my charging system this weekend as well.

griboflavin

Well, it worked just fine all weekend. So it appears to be intermittent.
Sometimes heated seats is better than no heated seats.
Thanks for the help!