After several years, two dealers and numerous jump starts I think I've found the source of the dead batteries in my 2000 C-5 convertible with memory seat. When I pulled the fuse for the "Driver Seat Control Module" the current flow (approx. 0.8 amp) stopped! Now I've got a bunch of questions!

1) Where do I go from here? That is, does the seat need to be removed for trouble shooting?

2) I would assume I need to look for frayed wiring under the seat?

3) Is the switch assembly separate from the control module?

4) Could the switch(s) that controls the forward/aft, up and down/pitch be the source (possible partially "on")? I assume I could check this with a volt/ohm meter. (of course this assumes there is a separate switch)

5) How would I check the Control Module? (by the way the lumbar support/side bolster pump has not worked for some time, would this be a function of a faulty Control Module?)

6) Can the Control Module be serviced/repaired?

I obviously do not have a service manual, so would appreciate all the advice any of you can supply!

 

The three most likely causes of the seat to draw excessive current are:

- Multifunction seat control switch. Sometimes the switch does NOT return to the center neutral position and the motor for one of the seat positions tries to run all the time. Each motor is protected by a resettable breaker (thermally protected) and once the motor cools off it turns on again till it trips the breaker.

- Seat Bolster air pump. If the seat bolster air pump doesnt see the correct pressure, it will run the pump continuously

- The memory seat uses feedback pots to tell the seat module where the seat are. If one or more of the feedback pots are not working correctly, it could cause the seat to continue to TRY position its self without success.

You can have a seat connector issues as it does and can hang low and when the seat moves, it gets damaged sometimes.

Try running the seat thru ALL of its positions to the MAX or limits several times. Turn the easy out function in the DIC Options to OFF (so it doesn’t go to the full reward and full tilt down position and see if the current draw issue stops.

Check that seat switch for the seat position and bolster switch. Make sure they are not staying in a position that operates something all the time.

Check the Air Bladder and air tubing for the seat bolster to see if its not deteriorated.

WHEW......... I think I got it all!



Bill

 

Bill, thank you.

I will investigate these suggestions. A comment and a question.

I don't think the air pump works at all. It has been at least three or four years since I've heard it operate. (The passenger seat pump does operate)

Again do I need to remove the seat to get to the driver seat control switche(s)?

Thanks!

 

If I remember correctly, you can remove the screws and take the switch assy out with the seat in place. Use the seat controls to jack the seat up high and you should see the screws.

 

Again Thanks!
I will try and work on this over the weekend.

 

I'm glad I saw this thread. It may be my dead battery issue too. My seat moves forward 2" every time I hit the unlock button with my remote.

 

Have determined a couple things:

1) Will have to remove the driver's seat to get access to anything.

2) Have verified the 0.8 amp draw to the Drivers Seat Control Module (DSCM) as follows:

Using a 0 - 10 amp meter in series with the negative battery terminal and the negative battery cable, pulled the 10 amp DSMC fuse and the 0.8 amp draw stopped.

THEN reconnected the negative battery cable, and plugged the amp meter leads into the empty fuse recepticle. (The amp meter was serving as a "fuse" or a "jumper") -- The 0.8 amp draw showed on the amp meter.

Deactivated the "auto seat retract" feature -- the draw remained the same.

Ran the seat fore and aft / up and down --- the draw remained the same -- there was no additional current draw!

SO, I'm confused! I guess the 10 amp DSCM circuit does not suppy power to run the seat motors. But only supplies power to the seat switches. Another circuit must suppy power to the "power" side of whatever relays that send the current to the motors. BUT one would think when these switches are moved there would be SOME change in the current draw -- I can't detect any.

Any thoughts? (I'm trying to eliminate everything possible before removing the seat, bercause that is probably a big chore.)

On what I think is a completely unrelated matter, the oil pressure guage "pegs out" whenever the engine is on or the ignition switch is in the "run" position. It returns to zero when the ignition is off.

 

Well,,,,,,,,,,, Now you may be into remove the seat time.

Check out the wires and connections and look for damage. You can remove the SCM and open it up. Look for corrosion, board damage, looks / poor solder joints, over heated relays.... ect......

Yes, the 10 amp fuse is control power. The CB is the main motor pawer.

Bill

 

Thanks Bill,

I will have to drive with a "fixed seat" for a while as I summon the courage to pull the seat!

Any thoughts on the oil gauge?

 

Oil pressure sensor is a VERY common problem. You will need to replace it. Literately thousands of posts about this.

 

Apologies to Bill!

Using a mirror I did find the recessed screw holding the front of the plastic trim piece upon which the DSCM is mounted. The rear of the trim piece seems to be held in place by the seat back handle. How is this handle removed? It appears to have a wire spring inserted into a slot at hub of the handle.

Thanks, Big Gun I'll go looking for posts on the oil pressure sensor. Would like to replace this myself unless it is a big job.

 

The handle is secures with a C shaped spring clip. I use a piece of stiff wire and bend a small very short " L " at one end.

If you push back the seat material, you can see the spring. Slip the hook under the spring and pull up on it and at the same time, pull off on the handle.

Be careful or you will lose the spring as they like to fly far and to places unknown.

Bill

 

(Partial) Success! Was able to get to the Driver Seat Control Module (DSCM) by removing the seat trim. Disassembled the DSCM and found a burned diode in the circuit for the bolster / lumbar inflation. Replaced the diode w/a Radio Shack 12 V diode (2 for $1.99). The DSCM, once reinstalled, functioned properly in that the seat moved up and down, forward and back and the memory seat function worked as before. While I could hear the relays for the inflation motors clicking, the motor(s) would not run. Believe they are cooked. Once I got the trim piece off the seat, I could reach in and feel the motors. One was hot to the touch, (before I replaced the defective diode). So the 0.8 amp drain has been going into the motor(s) all this time.

I probably will do without the bolster and lumbar functions as I really don't want to pull the seat to get to these motor/pump units.

Many, Many thanks to Bill for his help and support!!!!

I have made photos of the above process and will be glad to do a write-up with them, if there is interest. Will be "out of pocket" for the next couple of weeks.

OH, called the agency -- a new DSCM is $418.50. THATS when I started REALLY checking the DSCM I had!

 

Well this post has been informative, and just from the issues described, I feel like this is my exact problem as well. Time for some race seats!! Haha.

 

I want to correct something I posted earlier. After scanning a catalog of Corvette parts, I learned that I misidentified the component that had the defective diode. The diode was in the SWITCH ASSEMBLY not the driver seat control module (DSCM). According to the catalog, the DSCM is located under the seat, whereas the part I repaired was indeed the switch assembly, mounted on the plastic trim at the left side of the driver's seat.

 

YES,,,,, PLEASE post the pictures of the repair process. GREAT JOB on the successful repair.

YES,, YOU BUILT THAT!

Bill

 

My 2000 C-5’s battery was continually being drained and what follows is the search for the cause and the repair of the DSSU.

-With the hood up, ignition off, doors and trunk (hatch) closed; deactivate the under-hood light by following the wire(s) to the plug / receptacle and disconnect.

-Disconnect the negative battery terminal. Using appropriate bolt, nuts and copper wire, connect an ammeter (in series) with the negative battery “post” and the negative battery cable. (If an inductance ammeter is available, so much the better)

-If using a non-inductive ammeter, as soon as the series connection is completed there will be a clicking sound (or several clicks) heard from the area of the right headlight. (I believe this sound is coming from a relay in headlight motor circuit.)

-Once the connection is complete there should be a current flow of somewhat more than 1 amp. Over the course of several minutes, the draw from the battery should drop to approximately 25 milliamps as the various computers and electronic devices “shut down”. (The 25 milliamp draw is keeping the clock and other memory devices running while the ignition is off, and the car is sitting idle. In my case, the amperage draw never dropped below approximately 0.80 amps.)

-In order to determine the circuit where a defect is, it is necessary to pull and reinsert fuses until the excessive amperage draw is isolated. There are two fuse panels in the C-5: under the hood next to the battery; in the passenger foot well behind the carpeted panel. The fuse pulling process can be rather time consuming because as fuses are reinserted, devices will “wake up” and it is necessary to wait for them to again “shut down”.

(In my case the fuse for the circuit causing the excess draw was in the foot well fuse panel and was associated with the 10 amp fuse labeled, “Driver’s Seat Control Module” [DSCM]. I mistakenly thought the DSSU was the DSCM. The DSSU provides only switching power to the DSCM. It was not until I was looking through a parts catalog that I discovered that I was dealing with the DSSU, not the DSCM. [I Hope that is not too confusing!])

The following photos and descriptions show the process of checking and repairing the DSSU:

-The DSSU is mounted in the Driver’s Side Trim Panel

[IMG][/IMG]

-To remove the trim panel, the Seat Back Adjustment Handle must first be removed, and is accomplished by using a wire hook to engage and pull up on the spring clip holding the handle to its shaft. (Thank you Bill Curlee):

IMG][/IMG]

-The detail of the clip and wire hook is shown below:


-With the handle off, the trim panel can be removed by sliding the seat forward and tilting it up in front. This will allow accessing the recessed screw on the front of the panel. The second screw is adjacent to the shaft for the seat back adjustment handle.

-Shown below are the two screw positions and the retainer clips for the DSSU (taken of inside of the trim panel):

[IMG][/IMG]

-Once the trim panel is removed, it will be necessary to remove the DSSU by disengaging the retainer clips, only then can the DSSU be disconnected from the wiring harness.




(The DSSU is held in the trim panel with four integral plastic clips.)

-This photo shows the DSSU in the trim panel, but after it had been removed to disconnect the wiring harness, then re-installed in the panel:



In the photo below the two pencils indicate the two “sealing posts” that are either heat or solvent welded to the inner cover of the DSSU. (I pried the cover off, but believe I should have either carefully “drilled out” or cut the “welds”. Fortunately nothing broke employing my method!).

[IMG][/IMG]

-Below the DSSU case is open showing the two sealing posts (also some discoloration may be detected in the center of the circuit board near the center connector pins, this was a clue to a burned diode):

[IMG][/IMG]

(The seven cylindrical objects with the yellow stripes are the diodes. These were checked by comparing one to the other using an ohm meter. By the nature of a diode, direct current will flow in one direction but not in the other. The ohm meter supplied enough current to check them. The single diode on the right, above the pair of diodes and near the discolored area, was found to flow current both ways. This diode was one of those associated with the switches for the inflator motor.)

Here is a close-up of the defective diode:

[IMG][/IMG]

(One end of the diode has been unsoldered. When the DSSU was taken to the car and temporarily reconnected, the current draw was checked and determined to be in the in the desired 25 milliamp range.)

Here is the circuit board with a new 12 volt Radio Shack diode soldered in place. (A very low wattage soldering iron, used for miniature circuit repair, was employed for the unsoldering and soldering process.) Note the Radio Shack diode had a connector wire protruding from each end vs. the smooth ends of the original diodes:

[IMG][/IMG]

Reassembly was a simple process (I did not re-seal the back of the DSSU case, but “snapped” it together). Once everything was back together I determined that the inflator motor was “cooked” due to the steady flow of current through it—not enough current to cause the motor to run but enough to make it hot to the touch. The repair of the inflator motor will wait until a time when I summon the courage to pull the driver’s seat from the car. However, the DSSU is fixed, as I can hear the relays in the DSCM clicking when I move the toggle switches. And, now I have a car that can set for days without the battery being depleted.

For informational purposes only, below is a photo of what is on the “other side” of the DSSU looks like out of the trim panel:

[IMG][/IMG]

I hope this is not too long-winded, but is helpful to fellow Corvette owners. Again, I wish to express my thanks to Bill Curlee for answering my questions and providing the electrical threads he has posted.

 

WOW!! EXCELLENT write up! Thanks for the reply and info.

Post that on the Forum! Send me the link so I can follow the replies and such.

Bill

 

Thankyou very much Wes and Bill my battery started draining .08 amps about 2weeks ago I NAROWED IT DOWN TO THE Seat controll cicuit and was trying to figure out where to go from there when I thought of the forum. I pulled the DSSC a apart and found the same diode blown and soldered in a new one, like you Wes, I left the motor problem for another day. That said the seat is very easy to pull 4 15 mm bolts. Thanks again for the great pictures AWESOME.

 

I have a spare driver seat bottom frame with motors if you need one of them