oil & alt lights always red when lights turned on???
02-06-2008, 08:28 PM
#1
Thread Starter
Join Date: Jan 2008
Posts: 48
oil & alt lights always red when lights turned on???
Hello everyone, this electrical stuff is very frustrating. Has anyone here ever had a problem with their oil and alt light always coming on whenever the lights are turned on? It's a 65 mustang and I just had it serviced and so everything is good under the hood. Checked all fuses and replaced bulbs in instrument panel. I just don't know where to start as far as fixing these 2 things. If anyone has ever had this problem and found a way to fix it, please let me know. Thanks alot.
02-07-2008, 10:40 AM
#2
2nd Gear Member
Join Date: Jun 2007
Posts: 231
RE: oil & alt lights always red when lights turned on???
J-65
I have not had a chance to look at the wiring diagram (schematic) but would suggest you doing so.
I do not know your electrical knowledge so lets consider a few thngs:
(a) When you turn the ignition switch with your key to "On/Run" (not start) and the engine is not running, the ALT and OIL lights (often refered to as idiot lights) SHOULD illuminate since the Alternator is not generating any current and the Oil pressure has not yet built up. This is Normal.
(b)When the engine is started, and, once again the switch is in the "On/Run" position, the alternator begins to generate current and the oil pump increases the oil pressure - both of these actions result in the idiot lights turning off. Again, this is normal.
In ther words, these idiot lights should illuminate under two conditions if the system is wired correctly: (1) when the engine is not running and the ignition switch is "On/Run" and (2) the alternator is failing to produce current and/or the oil pressure is low. Importantly, neither of these idiot lights should illuminate when the ignition switch is in the "off" position; in the off positon, the current feed to these lights is off (i.e. no current)
(c) The headlights, on the other hand, normally operate when the ignition switch is in any position, even the "off" position. In other words, the part of the circuit feeding this component is always Hot (i.e.always on). If I remember correctly, the headlight switch (you pull the armature of this switch to turn it on) allows current to flow to the dimmer switch, which directs it to either the low- or high- beam lamps.
Given these circuit realities, it seems odd that this headlight switch would allow current from the headlamp circuit to flow to your idiot lights unless there is a strange short from a wire originating off the headlight switch (perhaps the wire that feeds the panel illumination lamp?).
A few questions first:
With the engine off (i.e. not running) and the ignition switch turned to the "Off" position, do the ALT/OIL lights illuminate when you turn on your headlights? If so, the source of your idiot light current is at or after the headlamp switch and I supect you have a short somewhere.
Do the ALT/OIL lights illuminate only when the ignition switch is in the "on/run" position, the engine running and the headlamps switched on? Again, I suspect the source of your current is at or after the headlamp switch and I supect you have a short somewhere.
Do the ALT/OIL lights illuminate regardless of the ignition switch position or if the engine is running and the headlamps switched on? Would have to do some investigaton on this one!
Answer these questions and it may help us figure out/ narrow down what is going on.
I have not had a chance to look at the wiring diagram (schematic) but would suggest you doing so.
I do not know your electrical knowledge so lets consider a few thngs:
(a) When you turn the ignition switch with your key to "On/Run" (not start) and the engine is not running, the ALT and OIL lights (often refered to as idiot lights) SHOULD illuminate since the Alternator is not generating any current and the Oil pressure has not yet built up. This is Normal.
(b)When the engine is started, and, once again the switch is in the "On/Run" position, the alternator begins to generate current and the oil pump increases the oil pressure - both of these actions result in the idiot lights turning off. Again, this is normal.
In ther words, these idiot lights should illuminate under two conditions if the system is wired correctly: (1) when the engine is not running and the ignition switch is "On/Run" and (2) the alternator is failing to produce current and/or the oil pressure is low. Importantly, neither of these idiot lights should illuminate when the ignition switch is in the "off" position; in the off positon, the current feed to these lights is off (i.e. no current)
(c) The headlights, on the other hand, normally operate when the ignition switch is in any position, even the "off" position. In other words, the part of the circuit feeding this component is always Hot (i.e.always on). If I remember correctly, the headlight switch (you pull the armature of this switch to turn it on) allows current to flow to the dimmer switch, which directs it to either the low- or high- beam lamps.
Given these circuit realities, it seems odd that this headlight switch would allow current from the headlamp circuit to flow to your idiot lights unless there is a strange short from a wire originating off the headlight switch (perhaps the wire that feeds the panel illumination lamp?).
A few questions first:
With the engine off (i.e. not running) and the ignition switch turned to the "Off" position, do the ALT/OIL lights illuminate when you turn on your headlights? If so, the source of your idiot light current is at or after the headlamp switch and I supect you have a short somewhere.
Do the ALT/OIL lights illuminate only when the ignition switch is in the "on/run" position, the engine running and the headlamps switched on? Again, I suspect the source of your current is at or after the headlamp switch and I supect you have a short somewhere.
Do the ALT/OIL lights illuminate regardless of the ignition switch position or if the engine is running and the headlamps switched on? Would have to do some investigaton on this one!
Answer these questions and it may help us figure out/ narrow down what is going on.
02-07-2008, 10:57 AM
#3
4th Gear Member
Join Date: Aug 2007
Location: Houston, Texas
Posts: 1,692
RE: oil & alt lights always red when lights turned on???
Have you tinkered with the bulbs in the instrument cluster? If so, maybe you got a regular panel illumination socket plugged in to the wrong (idiot light) hole on the instrument cluster. Do you see any dark spots on your guages when they are supposed to be lit?
If this isn't the case, follow mustangdoc's advice.
If this isn't the case, follow mustangdoc's advice.
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