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Re: 90 Seat heaters no workey; but voltage & heating grid OK? Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Wed, 20 Dec 2000 15:59:06
In Reply to: 90 Seat heaters no workey; but voltage & heating grid OK?, DET, Wed, 20 Dec 2000 15:08:07 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I think I know the answer to your problem - go to the bottom of the post. But to answer your questions-
To remove the heater controller from the dash-
It just pops in, so you should be able to pop it out - with some effort. Get a thin screwdriver or knife blade, and slip it in between the bottom of the switch and the square hole it sits in. You want to lever the bottom of the switch towards you *just a little*. Then do the same at the top. You want to 'walk' the switch out. It will eventually pop out. The controller is quite long. I always tie a string to the cable harness before I remove the controller, as the cable wants to dive back into the dash and disappear otherwise.
The controller is NOT a rheostat. It measures the temperature of the seat with a sensor. If the seat is colder than the temperature, a relay in the controller closes and applies 12 volts to the heater element. Once the seat heats up to the temperature setting (1 being colder, 3 hotter) the relay opens and NO volts go to the heating element. When the seat cools a little, the relay closes again.
The answer:
You are getting 12 volts to the heating element in positions 1,2, and 3. This tells me the controller is *probably* OK. Do this test:
Measure the resistance of the BLACK wire to ground. 12 volts to the heater do no good if the current has no ground return. My guess is that the ground is bad. If the resistance is more than a couple of ohms, clean up the ground connection and enjoy the heat.
OK, what if the ground connection appears good? You probably did the voltage measurements with the seat unplugged - namely, no load on the system. If you have a bad connection, you'll see 12 volts, but it may go away under load. This is a bit tricky, but try it. Measure the voltage to chassis on the supply to the seat heater under the seat with the Seat Plugged IN. You can usually stick the meter probe into the back of the connector. If you get less than 12+ volts, there is a problem in the power. It may be that the relay in the seat heater controller has dirty contacts. If so, remove the controller, open it up, and clean the relay contacts with some fine sandpaper.
If you see a good 12+ volts on the high side of the grid, measure the voltage on the black wire to ground. It may measure 0 or so ohms with no load, but under load a bad connection will show up. If you see more than about 200 millivolts (0.2V) between the heater side of the connector and chassis, clean the ground point AND the connector contacts.
I hope this helps.
, Wed, 20 Dec 2000 15:59:06 <-- Viewing This Message, Thu, 21 Dec 2000 10:01:01, Thu, 21 Dec 2000 13:25:18, Fri, 22 Dec 2000 08:55:43
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