Heya all. So after losing a thermostat seal and spewing hot coolant everywhere I wondered just how hot my car was getting. I just did a head gasket on her the first week of July and it'd sure be nice to not go through that mess again. The TEMP idiot light never came on, so I figured, at least it's not hot enough to blow up or anything. Then I kinda...wondered...about how those idiot lights worked. The only one that comes on when I turn the key is the ALT light, which of course goes away as soon as the motor is started. I've never seen what the other warning lights are but I assume they're OIL, BRAKE, TEMP and... gee, I have no idea. SEATBELT? My car did have that nasty seatbelt interlock system but it was bypassed at some point in the past and no longer functions. Which is to say, the car actually starts reliably. So I unplugged the water temp sensor and grounded its connector with the key in. Success, there was the big bright TEMP light. But that was grounding it, which is what the sensor is supposed to do only when it's super-hot...right? What I'm wondering is, are all five of my idiot lights supposed to come on when I turn the key, or just ALT? I at least know my TEMP light and its subsequent wiring is working which is great, but now I gotta know if the sensor is bad or if it's just doing exactly what it's supposed to. Thanks!
Tim and I were just talking about the temp light yesterday. at what temp does it come on ...I have seen 235 degrees on a gauge and no light...
Dang... so considering that the only light to come on is ALT, that means I've lost at least three. I'll ignore the FASTEN BELTS for now... So with the knowledge that the TEMP light will come on if the connector (the little nub that goes onto the back of the temp gauge in the head) is grounded, and assuming that this goes the same for whatever sensors are used for OIL and BRAKE... what's the diagnosis? How exactly are these supposed to come on before starting the car? Are all the sensors bad somehow, or is there some other issue with how the 'pre-start check' system works?
I'll do that for the BRAKE and OIL lights, but the TEMP one comes on so it's fine. I'm just wondering how exactly the light 'knows' to come on when the car isn't started and 'knows' to go out when it is. There's only one wire coming off of the 'sensor', so... it's either grounded or it's not, right? It's just a switch, yeah? In any case, will check the bulbs on the other two in the morning.
Imnot here to starttrouble BUT can you say the problem again im thinking that if driving a modern day car when you turn the key ac the idiot lights come one first, the same for these lil mav's if not wiring problems along with bulbs being burnt out are the ovious, and the problem that results is the crafty ness of oil water and temp guages being instald with a bracket screwed to the dash because someone didnt do there home work and know that every thing has a + to -... Im saying if the temp gage doent work its a bulb or the sensor on the block or wires got messed up, same for oil and gas exctra to put in a lam but fun way. These cars are so old some been siting so long that natures lil criters like copper and other materials ase much ase!!
If there were gauges installed I probably wouldn't be asking. Heck I'm tempted to install a water temp gauge anyway at this point. The problem is that apparently, all the idiot lights are supposed to come on when you turn the ignition on, then go out once you start the car. Only my ALT light behaves that way. That makes perfect sense since the alt light is lit by the battery with the ignition on, then is cancelled out by the alternator signal current once the engine starts running. The thought was that maybe the bulbs were dead, but grounding the water temp sensor connection lights the TEMP bulb just fine. So the suggestion there is 'bad sensor', but I'm trying to get some technical insight as to why that is. I guess I just don't get how the idiot lights can all come on before starting then go out afterward when they're all linked to single-wire switches that just go to ground. There's no computer in the car doing diagnostics, so how does that work? That's what I'm asking, I guess.
Works the same way my fan works.....ground the sensor, and the fan comes on. With the light, it is the same, the temp light comes on when the high temp is reached and the sensor grounds the light circuit.
The same way bying the after market kit from napa works, friend sensor s read in diferent ways some for hot some for cold some do things that make me mad when I get the wrong one. Water then it gets hot that sensor gets activated sending all that to a guage; gauge is grounded, guage is hot and it has a light. You have to wire these things up for the aftermarket one im saying its already there its just having a fail in the system. There is four varibles is there a ground is ther a hot wire with fuse is there a light is ther a connection to all and to a sensor on the engine block.
I think you're misunderstanding the question. The entire system works. Allow me to illustrate using your four variables. Is there a ground? Yes, the head. Is there a hot wire with fuse? Yes, as illustrated by the light coming on when the connection is grounded. Is there a light? Yes, it illuminates when the connection is grounded. Is there a connection to all and to a sensor on the engine block? Yes, that's what you can ground to get the bulb to come on. So I've cleared all four variables, but that merely covers the normal operation of the bulb after the engine is running. I know how the idiot lights work once the car is running. The sensor grounds the connection once it has reached a certain temperature. It's an on/off switch. It hits 245F (or whatever), grounds, and bam you have a TEMP light telling you why your motor just exploded. What I'm asking is how that light is supposed to come on when the engine is not running and the key is in the on position, prior to actually turning it to the start position.
