Hello fellow 355er's Some of you may know I recently replaced my 1999 Spider top and re-activated the hydraulics. The PO cut the wires and made it a manual top. Pretty sure because he could not get the rams synchronized. So my question: 3 sensors: activates the windows when the top is unlatched (works great) activates the Potentiometers when the switch is activated to lower the top (there's the rub) activates the windows when the top is down (works great) So want to be methodical in my assessment of the seat potentiometer. Is there a test (volt meter, jumper) to determine if the switch works? Paperwork from the PO indicates the potentiometer's were repaired, but can't trust that. Both seats do not move. Thanks Brothers and Sisters. Boaf
Seats only move if the computer thinks that it is NOT in the middle of a roof cycle. So the top has to be totally open, or totally closed. I would some how get to the motor wires (2) and apply 12 to them to see if the motors work (likely do). Now you can remove the seats from the car, remove the pots from the seats, and test them with a ohm meter. In the very end, you still need access to an SD1 in order to teach the car how to operate the seats. That is getting very hard.
Not sure what you mean. Do you mean "activates the seat motors"? I assumed that there would be power to the potentiometers at all times with the ignition on (?). Do you get the correct beep when you manually pull back on the roof prior to using the roof switch? With the roof closed, do both seats work with the manual seat switches? Does the roof switch close the roof with the seats manually driven fully forward? Are the potentiometers, motors and orange jumper wires under the seats all connected? Have you checked to see if the roof switch is connected at all? Sorry if you've answered these questions before. I recall the potentiometers have a range of a few ohms to around 4k or so ohms. The 3 pin plug outer pins will always be 4k and combinations of inner and outer pins will vary with seat position. Like all potentiometers, the sum of the inner to outer pin resistances should approximately equal the outer pin resistance. Power comes in on the grey-yellow wires.
One thing to check is that the seat pots should read 4.4k ohms between the pink and yellow wires when the seats are fully forward. It is my understanding that the reason the seat pots have the friction ball joint (see below, similar but not 355), that frequently fails, is so that the seat pots can be correctly set by moving the seats fully forward then fully back. If the pot reaches the its limit of rotation before the seat is fully forward or fully back, the ball joint slips until the seat is at full extension, thus setting the pots correctly. Image Unavailable, Please Login
How do you know what value is in the ECU? Boaf, I assume you still have the seat diagram? Fig49_1998_Roof_Electronics_1998 If you have access to the ECU, you could always check the seat potentiometer resistances at the ECU plug (to make sure the wires to the potentiometer are ok). You can also check the seat motor wiring at the ECU end. I guess you could also check the roof switch input into the ECU.
Letting it slip is fine but not how they were set. Once installed the computer directed you to put seat at full forward position, then at full rearward position and remembered the values. The pot had much greater range than the seat travel needed. The values from right seat to left seat could be vastly different even though their travel as executed by the top moved them to the same position. It has been a lot of years but I seem to recall the seat from full forward to full back only uses 1500 ohms or so of the pot range.
Have the ECU move it then measure the pot. Then full range the seat and adjust POT to what the ECU has told you its limit value.
This is what I did to my spider. I ran a set of wires to the motors you I can always apply 12V or -12 to the motors to move the seats. Then, I removed the seats, and removed the pots from the motor shafts. I wound the pots all the way to one end (cannot remember which end, minimum or maximum) and hanged them off to the side under the seats, not engaged to the motors any more. The top ECU now thinks that the seats are always shoved up against the steering wheels because the owner is a midget, and the top ECU always works. There is only one small compromise, the seats must be manually moved to the front before I operate the top, but that is a very small price to pay.
Thanks, I did remove the seats when replacing the top. The only thing I did was plug them back in. Do they really need an SD1?. I need to review all the comments too, man who would thought removing a seat needs to re-train the seats from the ECU.
It is easy enough to make them work as designed. Like I said, have the top system cycle the seats forward and read the pot value. Then move the seats with the seat switch full forward adjust the pot to the value you measured and reinstall on the motor shaft.
Thanks for the diagram. I will be able to work on the Poteniometers in a few weeks. working on the adjusting to get the forks to engage without me having to stop and push them in place. Boaf
Good luck, Boaf. Meanwhile, I'm still waiting for the 3M canvas adhesive to arrive in the mail. After two failed purchase attempts (due to USA postage restrictions on volatile materials), I won't start pulling my car to pieces until I have the adhesive in my hands.
Thats usually caused by the main mounting bolts allowing the mount to shift to an unfavorable position.
