Some places to start looking:
There is a fuse feeding the relay (16A?) in the fuse box. There should also
be power fuses (25A?) from the relay to the seat switches.
If all good, check if the relay is working.
Also possible is a problem in the door switch circuit that controls the
relay (your seats move with ignition off and doors open).
The seat switches themselves are known to go out on these cars too - but
usually not all 3 sections at once. A bit expensive, but easy to replace.
email@example.com (kbm) wrote in message
Thanks Scott. I checked the fuses. The fuses for each front seat look
good. I replaced them anyway but still doesn't work. I figured that
since both front doors went out at exactly the same time it probably
was't the fuses.
Where is the relay and how do I check it?
It seems like if it was the door switch then it would not function
with either the ignition on or doors open but if you can't adjust the
seats with doors open nor with the ignition on it doesn't seem likely
to me. But I am not knowledgeable in these things so anything you can
suggest would be helpful and appreciated.
I noticed last night that the dome light doesn't come on when I open
the door and none of the 3 settings work when I switch it on from the
inside. Is this related?
Is there a way to manually adjust the seats? The passenger seat with
the back all the way reclined.
Thank you for all you help.
From the fact that they do not work with either the doors open or with ACC
power on, it could be the relay but you should check everything else too.
There are 4 fuses to check. The relays are in the rear section of the fuse
box but I cannot remember which one is the seat relay - maybe your owner's
manual will help. To get to the relays, remove the fuse cover, then remove
the screws holding the rear portion of the cover.
- The seat relay is powered by a 16A fuse (#2) via a diode with the ACC on,
or it is powered through a 8A fuse (#9) via the door switches.
- Mechanical relays like these will click noticeably - so listen carefully
while someone operates the seat switch with door open or ignition on. You
can also check the relay for certain by removing it and measuring
resistance across the input pins, and if that is OK check the output
contacts by putting +/- 12v on the input pins while checking continuity on
the output pins. Or, just get a new relay from the dealer if you are not
comfortable with a Volt/Ohm meter :^)
- The relay (if working), sends high current to the seat motors via two 25A
fuses (F and E). So there is a possibility these fuses are out. btw I do
not think the two fuses are left and right seats, but rather for the
- From these fuses the power goes to the seat switches and the driver-seat
The only connection I can think of between the overhead light and the seat
relay is that they both are powered by the same fuse (#9) via the door
switches. If fuse #2 and fuse #9 were both out, the seats would not work and
the light would not work.
The only way I know to "manually" operate the passenger seat back is to pull
the seat switch or the plug under the seat, and put +/- 12v across the gray
and orange wires. Seat back direction depends on which wires you put the +
and - 12v on. This is not hard if you are comfortable with electricity and
can double check yourself.
It is important to note that fuses in these cars are notorious for
developing very slight oxidization on the tips that fit into the small holes
of the fuse holder. The fuse may look good but still not pass current. So
remove the fuse and either replace it or clean the tips with fine sandpaper.
Some auto part stores have glass enclosed fuses with stainless ends that are
very nice replacements!
If you can't find those, at least buy replacement fuese which are copper
alloy (golden), rather than the tin alloy (silvery) ones, which turn
powdery and develop hairline cracks.
Swapped all of mine in the 123 and 124 and have not had any problems.
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