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Headlight switch turns on oil light |
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sweatlock
AMC Addicted Joined: Apr/28/2014 Location: Largo, FL Status: Offline Points: 3322 |
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Posted: May/19/2022 at 7:25pm |
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Okay, this is a really weird one and I need some help -
1969 AMX, all new wiring harnesses throughout bought from APD, new headlight switch (old one did the same thing), all copper sheet grounds in place on the plastic dash PLUS an extra ground wire going to the firewall up to the copper ground for the clock/instrument panel. The problem is that when I pull out the headlight switch knob to turn the headlights on the red ‘OIL’ idiot light comes on; the light doesn’t come on with just the running lights on (first pull-out on the headlight switch). Did a site search, nothing. Did a Google search, nothing. This is disturbing to say the least when driving at night. Has anyone else experienced this? What the eff could it be?
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tufcj
Supporter of TheAMCForum Supporter of TheAMCForum Joined: Jul/10/2007 Location: Watkins, CO Status: Offline Points: 4097 |
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Wire misplaced in the harness, high beam indicator maybe? Short in the circuit board on the dashboard? Bob tufcj
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69 AMX
74 Javelin AMX 67 Rogue If you need a tool and don't buy it... you'll eventually pay for it... and not have it. Henry Ford |
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PeterS3
AMC Apprentice Joined: Apr/22/2022 Location: Wyoming Status: Offline Points: 35 |
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The only thing that I've had that was similar to this was my trailer brakes coming on when I turned the left turn signal on. That was caused by two wires melting together after I welded a crack in a frame on an old truck.
It's going to be a pain to track down. You're probably going to have to unwrap lots of little places in the wiring harness, and cut the wires to do continuity tests between the oil light and the head light switch. I've had good luck with adhesive heat shrink tubing, because it has hot glue inside the shrink tubing that keeps the water and salt out. Any time you cut a wire, make two solder joints with a 1-2 inch wire in between the cut ends so that all the stress of the wiring harness moving around isn't on that one wire joint.
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304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
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Does the oil indicator light up with headlights off, ignition on while engine is not running?
If so, that is good, but when headlights are on, and engine runs... the issue is ground path. The wire to the oil pressure switch is getting grounded by headlight switch. It is possible the headlight connection on the harness could have a crossed wire. If you have the original harness, you can compare. |
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71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
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BU1
AMC Addicted Joined: Aug/11/2016 Location: MN Status: Offline Points: 2019 |
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Does the headlight switch have the spade terminal on the back to connect to a ground wire in the harness?
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AMO #2726
#1 1968 AMX Rally Green 343 Z code 4spd since 1975 #02642 #2 1968 AMX Rally Green 290 N code 4spd since 2019 #02959 |
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sweatlock
AMC Addicted Joined: Apr/28/2014 Location: Largo, FL Status: Offline Points: 3322 |
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Yes
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sweatlock
AMC Addicted Joined: Apr/28/2014 Location: Largo, FL Status: Offline Points: 3322 |
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Oil light comes on with headlights off, engine off, ignition switch on. Oil light comes on with headlights on, engine/ignition switch off. Oil light does not come on with running lights on, engine/ignition switch off.
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sweatlock
AMC Addicted Joined: Apr/28/2014 Location: Largo, FL Status: Offline Points: 3322 |
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New circuit board as well. Both you and 304-Dude have mentioned checking the connector wiring at the headlight switch and comparing it to the original - I still have the original wiring harness so I’m going to have to do that. Hopefully that’s it.
Edited by sweatlock - May/19/2022 at 8:27pm |
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mixed up
AMC Addicted Joined: Jun/16/2015 Location: Monroe mich Status: Offline Points: 2178 |
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sounds like you have gremlins in the system
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69 amx 290 auto
65 220 290 4spd 80 ford fairmont |
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troutwilly
AMC Addicted Joined: Sep/14/2007 Location: Carriere, MS Status: Offline Points: 994 |
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Oil light comes on with headlights off, engine off, ignition switch on. - Tells us the oil pressure switch might be triggering the light. -- What happens in this situation if you disconnect the wire from the sending unit? --- If the oil light doesn't come on when the wire is disconnected then the sender circuit is probably correct. Oil light comes on with headlights on, engine/ignition switch off. - This tells us there is probably another signal to the light coming from the headlights. -- Is there any change if you press the high/low beam foot button? -- And again, what if the sending unit wire is disconnected? Oil light does not come on with running lights on, engine/ignition switch off. - This makes me think the errant signal to the oil light is not coming directly from the headlight switch. If your oil light still comes on when headlights are turned on, even with the oil pressure wire disconnected and ignition switch off, I'd say something is mixed up in the gauge wiring with the headlight indicator wire, especially if the oil light comes on and off with the changes in the high/low beam switch.
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Bill O.
70 AMX |
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