Help please: glitch in 4Hi + HD quad wiring, and I used schematic!

[DennisT]

I began studying this subject back into last winter. Finally got bits and pieces of time and parts to convert my 1996 GMC K1500 back to 88/89 glass quad headlights using LMC's upgraded lamps, (that they had so much trouble keeping in inventory). All grill and headlight stuff is done. I found the attached wiring diagram a poster did on these forums. Seemed to be the best I found. Finished all of it today except laying down the 12ga. individual power wires to the actual headlamps. So I checked my work. Low bean trigger wires and high beam trigger wires seem to actuate the proper relays just fine. (I'm using the original wires from the GMC headlight switch.) I switch on low beams in cab. Sets the right relays and I get pass-through continuity/actuation on the high current coils. Then I click the steering column stick to high beam. Blue lamp comes on on dash. Now both relay sets actuate so I know I'll be getting all four headlights on together. WhooWheee. Oops. when I click the lever to go back to low beams only, the blue light stays on on the dash and I still have all four feds to headlights on. Ahhhhh. Somehow, I've created a, "latching," relay circuit. If I turn the headlight switch OFF, then back on it's fine again until I try to return from high beams to low beams. Latches again.

You must be registered for see images attach

I think I might need a diode, but don't know where to put it or what diode to get. Can anyone look at this diagram and tell me how to fix this??????? I'm right in the middle of it all after all this time and I've got to solve this.
Thank you to anyone who can help. Dennis in E WA state

 

[DennisT]

I thought obvious, but the simple question, i guess, is: is this circuit a good circuit as drawn? If so, the problem must be.....me. I just need to know which. Thanks.

 

[DennisT]

OK, I solved this myself. Schematic is correct; it's a good circuit, just misleading. At least to me. I'm attaching a corrected copy. Compare the two drawings. Notice where the, "low light plug," lead in GREEN enters the relay. It appeared first to me that all those green lines were common. Not so. the break in lines in the drawing I thought to be common due to line color. In today's included drawing I've drawn a, "skip over," line within where my light pencil circle is. That's a more traditional way to show the wires there do NOT connect. Another identical situation a little below that preceding another relay. Another different but misleading intersection of lines is to the

You must be registered for see images attach

right where headlights are shown. I didn't correct that, it was obvious to me. My dash/blue light now goes off and on following high/how as it should be. Finally I can now wire the 12ga. power leads up to the relay pack and finish this darned mess.

 

[DennisT]

Finished everything. All lights work as they should. So just for forum members' reference, the above amended circuit diagram does, indeed, work as intended. Thanks to the original poster. Dennis

 

[Steve A]

The following information is intended for novices, "old" heads probably already know all this. That said :
In the schematic, the "Low" and "Hi" relays could be 4 pin relays while the "4 Hi" must be 5 pin. 5 pin relays have an 87 and 87a pin, some have pins 87 and 87a both normally open (NO) and others have pin 87 is normally open (NO) and 87a is normally closed (NC), I think but double check that. The one needed in this case is the more common 87 (NO) and 87a (NC). On the 4 Hi relay, hook the Lo beam trigger wire to pin 87a and the Hi beam trigger wire to 87. The common wire on pin 30 would then feed thru the switching coil of the Lo beam relay. 5 pin relays can be used for all three relays in this schematic, just make sure that the power feed to the headlights are connected to pin 87 on both the Lo and Hi beam relays. The added benefit to using all 5 pin relays is that only 1 spare need be carried.