Murphy Posted December 30, 2013 Share Posted December 30, 2013 As I've pulled the dash out this weekend to replace the clock with a Shiftworks tach, I've come upon a question. Since I have the stock "idiot" lights, when I turn the key to the 'accessory' postion, the 'idiot' lights illuminate. For those who have the gauge package, how do you know when your key is in the 'accessory' position? Quote Link to comment Share on other sites More sharing options...
Toppless72 Posted December 30, 2013 Share Posted December 30, 2013 The oil light comes on. Quote Link to comment Share on other sites More sharing options...
Mr70Monte Posted December 30, 2013 Share Posted December 30, 2013 there should not be any dash lights come on with the key in the "Accessory" position. They will come on with the key in the "ON" position. Quote Link to comment Share on other sites More sharing options...
Murphy Posted December 31, 2013 Author Share Posted December 31, 2013 The oil light comes on. Oh, that's right, the factory tach has the oil light. THX! This being my 1st first gen Monte, I'm not up to speed on all the other options/accessories....... Quote Link to comment Share on other sites More sharing options...
72jrfan88 Posted December 31, 2013 Share Posted December 31, 2013 I had a similar question. Everytime we start these cars is the oil light supposed to flash red as well as the temp and gen lights? I have never got these lights to illuminate so I guess If im running hot it would be nice to know. Could it be just bad bulbs? If so are they just red 194 bulbs? Quote Link to comment Share on other sites More sharing options...
Toppless72 Posted December 31, 2013 Share Posted December 31, 2013 Here's how the system works... Â Each dummy/idiot/warning/tell-tale lamp has one side of their filament connected to switched ignition power, meaning the other side needs a low resistance path to ground to make them illuminate. Â When you turn the key to "on" switched battery power on the pink dash wires provides the 12 volts. Â Since the engine isn't running yet, the oil sender's terminal is grounded, so the oil light comes on. Â If the emergency brake is engaged or there is an imbalance of pressure in the system, that brake sender line is grounded and the brake light comes on. Â Since the engine isn't running yet, 12 volts is being sent via a resistance wire into the voltage regulator where the field relay hasn't activated yet, this relay is providing this path of limited current to the rotor aka field in the alternator to ensure charging will take place due to the magnetic field that is being created. As soon as the engine starts turning the weak magnetic field of the spinning rotor induces current in the stator windings. There is a tap in the windings of the stator that is used as a "health check", this is the relay line (white wire) that sends roughly less than half normal system voltage back to the voltage regulator's field relay. With enough voltage to trigger the field relay, it pulls in and links battery voltage to the voltage regulator relay (the other relay inside the voltage regulator) and thus controls how much current flows into the field of the alternator to keep system voltage at the proper level. When that field relay picked, it also put 12 volts on the other side of that resistance wire. The GEN light is basically in parallel with the resistance lamp, so with 12 volts on each side of the bulb, there is no potential difference and the bulb goes out. Â If the engine stalls, or there is an alternator failure, that white "health check" aka relay wire looses power, relay looses power and now the dash bulbs other side sees low resistance path to ground, thus bulb comes on. Â What I just explained is for externally regulated alternator set-ups. Â When you turn the key on, the temp or hot light doesn't come on. GM provided a lamp test circuit so the driver is certain the bulb isn't burned out at start-up. Â When you hold the key in on the "cranking" position, the key switch actually sends a ground out to the other side of the hot/temp bulb and it lights up. This lamp test line is simply spliced into the temp sending line on a dummy light car. Quote Link to comment Share on other sites More sharing options...
Murphy Posted December 31, 2013 Author Share Posted December 31, 2013 Thanks Joe! Great explanation. Since I'm installing a Shiftworks tach in place of the clock and when I convert to gauges vs indicator lights, I guess the only way I'll know if the key is in the ON position is from the display of my RetroSound radio. Quote Link to comment Share on other sites More sharing options...
Toppless72 Posted December 31, 2013 Share Posted December 31, 2013 Murphy, Â My complete edit didn't get coppied in my last post. This explaination came from a wiring forum at another web site. This is how it works but I didn't write it. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted December 31, 2013 Share Posted December 31, 2013 your oil light will still come on since a gauge package does not have a oil pressure gauge and also they have a amp gauge which will show a discharge with the key on Quote Link to comment Share on other sites More sharing options...
72jrfan88 Posted January 1, 2014 Share Posted January 1, 2014 Great explanation. I however even when cranking the engine have never seen any of those gauges light up red.so I must have a bulb out. My light for the parking brake does show red when engaged and when my brights are on my light is blue. Those are the only ones I see working as of now Quote Link to comment Share on other sites More sharing options...
Murphy Posted January 1, 2014 Author Share Posted January 1, 2014 All the bulbs are clear, there are colored lens in the dash for turn signals, hi-beams, and brakes. If your oil or temp or gen indicators don't light up when starting then you most likely have several lamps burned out. Of the 17 lamps, I had 4 burned out, am installing the GE168 bulbs as they are brighter. Quote Link to comment Share on other sites More sharing options...
72jrfan88 Posted January 1, 2014 Share Posted January 1, 2014 Ok thanks. Is it easiest to just pull the dash pad to change these? I initially tried just taking screws out of gauge faceplate but everything was so tight after the screws were removed and I didnt want to crack anything. Any tips? Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted January 1, 2014 Share Posted January 1, 2014 you have to take the screws out all the way across the front edge of the dash pad Quote Link to comment Share on other sites More sharing options...
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