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Subject: checking the heater valves Author: shogun (moderator) : member since March, 2004 : 12552 posts Posted on: 2007-07-09 23:38:33

From ignition key position 1 (radio can be switched on) the heater valves get 12 V.

As they get only impulses the usual method to test with a digital multimeter (DMM) is limited, as it always only shows the middle/average value.
Switch the thumbwheel on the IHKA control panel to 28 degree C (max), then the +V line should be interrupted/cut off to the heater valves. At minium 16 degree C. ground/mass is fully on the valves, so that the valves close completely to interrupt the water/coolant flow thru the valves.
Best way to test is to use one of the old style test lights (cord test light) with the thin pin to pinch thru the isolation of the wires of the heater valve wiring. With this way of checking one can test if the problem are the heater valves or the control panel/module.
At max. 28 degree C. the light should be fully/always off, at 16 degree C minimum temperature the light should be fully on. In between 16 and 28 degree adjustment the light should blink, but in different intervals depending on the adjustment. Best is to switch the blower fan to max also, as otherwise the heater valves are adjusted automatically by the system, and the blinking frequency is reduced.
There are more simple ones with only a bulb inside, but I use this one, can even test the ignition cables


E32 750iL 11/88, E32 750iL Highline 03/90
7 series Tech tips
http://tinyurl.com/3486c

• checking the heater valves (pic) - shogun 2007-07-09 23:38:33 (1832 views)
  • The best wat to test? - Johan750 2007-07-10 15:47:49 (240 views)
  • additional info on the cable colors - shogun 2007-07-10 09:03:56 (233 views)
    • Re: additional info on the cable colors - robke 2007-07-10 13:54:00 (239 views)
      • Sorry , stupid Q , should have read the posts below first :-( (nt) - robke 2007-07-10 17:38:18 (202 views)