yeaterday i went out to my 1990 trofeo and i noticed that the inside lights didnt come om when i opened the door, then i tried to the lights on manual by the light switch and nothing, i check all the fuses in the glove box and nothing was blown , any help where to look next????

 

<H4>This problem manifests itself as having no dash lights at night. Also the headlamps do not come on automatically (with the twilight sentinal sentinal option), and the interior lights do not come on at night when you lift the door handle.</H4>
<H4>Other electric units work normally (taco, radio, everything else basically). </H4>
<H4>Almost certainly the twilight sentinal sensor has failed, though there are other possibilitites. This FAQ only covers a simple test for twilight sentinal failure and is not an absolute test. It is inexpensive and quick though. </H4>


The test is to remove the sensor. Please read all the way through.
<H4>To remove the sensor: </H4>
<H4>1. Repeat slowly after me: "I will not drop the sensor down the air vent" (3 times) (It is a bummer if you do drop it. Big time. &lt;g&gt </H4>
<H4>2. Remove the grille on top the dash under the windshield. Just pulls up and out. Bit fragile due to its length. </H4>
<H4>3. Locate the twilight sentinal sensor, in the center of the dash. It is blue and has a flat top. Look from outside the car for a better view. The other clear plastic dome sensor is the sun load sensor. </H4>
<H4>4. Remove the twilight sentinal sensor by pulling vertically upwards. It is pushed in like some small dash bulbs. Do not drop down the vent (!). </H4>
<H4>5. Now switch on the ignition (and make sure that you have slid the horizontal twilight control dimmer pot on the lefthand control cluster away from the full left setting). The car "thinks" it is dark so the headlamps come on with the dash lights etc etc. This is more obvious at night... (This is how I had my trofeo until a new sensor arrived so I could see the dash gages at night, it took me about 15 seconds to put the sensor in/out)</H4>


If putting the sensor back switches the lights off again, you are near certain that the sensor has failed. You can purchase them from GM.





You can check the sensor readings through diagnostics, BCM data value: BD44.


To enter diagnostics click this here for instructions.








Background infomation.





By using the diagnostics capability I established the following behaviour.


The readings are as follows:



<TABLE cellSpacing=0 width=238>
<T>
<TR>
<TD vAlign=top width="58%">
BCM BD44 Value</TD>
<TD vAlign=top width="42%">
Resistance Reading ohms</TD></TR>
<TR>
<TD vAlign=top width="58%">
1</TD>
<TD vAlign=top width="42%">
500</TD></TR>
<TR>
<TD vAlign=top width="58%">
2</TD>
<TD vAlign=top width="42%">
1000</TD></TR>
<TR>
<TD vAlign=top width="58%">
4</TD>
<TD vAlign=top width="42%">
2200</TD></TR>
<TR>
<TD vAlign=top width="58%">
9</TD>
<TD vAlign=top width="42%">
4700</TD></TR>
<TR>
<TD vAlign=top width="58%">
19</TD>
<TD vAlign=top width="42%">
12000</TD></TR>
<TR>
<TD vAlign=top width="58%">
35</TD>
<TD vAlign=top width="42%">
27000</TD></TR>
<TR>
<TD vAlign=top width="58%">
62</TD>
<TD vAlign=top width="42%">
52000</TD></TR>
<TR>
<TD vAlign=top width="58%">
78</TD>
<TD vAlign=top width="42%">
180000</TD></TR>
<TR>
<TD vAlign=top width="58%">
92</TD>
<TD vAlign=top width="42%">
560000</TD></TR>
<TR>
<TD vAlign=top width="58%">
93</TD>
<TD vAlign=top width="42%">
680000</TD></TR>
<TR>
<TD vAlign=top width="58%">
94</TD>
<TD vAlign=top width="42%">
820000</TD></TR>
<TR>
<TD vAlign=top width="58%">
95</TD>
<TD vAlign=top width="42%">
1000000</TD></TR>
<TR>
<TD vAlign=top width="58%">
96</TD>
<TD vAlign=top width="42%">
1360000</TD></TR>
<TR>
<TD vAlign=top width="58%">
97</TD>
<TD vAlign=top width="42%">
1640000</TD></TR>
<TR>
<TD vAlign=top width="58%">
98</TD>
<TD vAlign=top width="42%">
2000000</TD></TR>
<TR>
<TD vAlign=top width="58%">
98</TD>
<TD vAlign=top width="42%">
2040000</TD></TR>
<TR>
<TD vAlign=top width="58%">
98</TD>
<TD vAlign=top width="42%">
2720000</TD></TR>
<TR>
<TD vAlign=top width="58%">
98</TD>
<TD vAlign=top width="42%">
3000000</TD></TR>
<TR>
<TD vAlign=top width="58%">
99</TD>
<TD vAlign=top width="42%">
4000000</TD></TR></T></TABLE>