simple question about gauges! need some beginner advice :)

[sempaipaul]

Guys,

So I have been round cars for quite sometime - and have a rather simple question for you:

There are a bunch of mechanical sensors on these 911's and I am trying to replace what needs to be replaced on my newly acquired 79 SC 3.0

I have identified all of the following gauge identifiers with a letter and what I am looking for is 1. What exactly does each of these gauges show (and how accurate are they typically) 2. What sensor (and what is its location on the vehicle) that is responsible for it? 3. What should the normal readings read as the vehicle is warmed up.

Thank you for all your help!!


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[Hnichols]

A: oil level. I find it helpful when filling up the oil (with the car warm and running), but most will tell you that one shouldn't rely on it. Instead check the dipstick directly.

B: Oil temp. 9:00 would be normal when the car is at operating temp. May take 20 min. or so of driving to get it to that point.

E: Oil pressure. Mine reads at about 4 when I'm driving along at 3K rpm, between 1 and 2 at idle.

C and D: I think alternator, oil pressure, and bright lights, but someone with an SC can confirm.

Someone more knowledgeable than I can tell you where the respective sensors are.

[timmy2]

A. Sender is on the oil tank in the wheel well.
B. & E. are on the right side of the fan housing. Pressure sender above the temp sender.
C. Is idiot light sender mounted behind the CIS on top if the engine..
D. Is part of the charging circuit. Wires run to the voltage regulator and alternator.

[DRACO A5OG]

These Gentlemen summed it up well.

Now go drive her like you stole it

[porwolf]

Here is page 14 of the manual of my all original '79SC. E-mail me if you need a larger resolution.

[sempaipaul]

Great! Thanks guys!

So that D red light stays lit for me all the time even when I turn off the car. What do you think could be the issue?

Thanks
Paul

[DRACO A5OG]

Alternator/Battery Light, even with the ignition key out of the car?

[sempaipaul]

Alternator/Battery Light, even with the ignition key out of the car?

Correct the light is red even when I take the key out of the car

Thanks
Paul

[DRACO A5OG]

Oh my, that is a problem, very strange. Does your battery drain out from it being on all the time?

[porwolf]

Well the way I see it is that the generator light somehow is hooked up wrong This is the way it is supposed to be connected:

From the Bentley Service Manual:



Basically it seems the generator warning light is supposed to come on if +12V is supplied from tab 15 at the ignition switch and ground comes from the generator/alternator. If the generator/alternator is functioning correctly that connection should be at ground level and the light goes off because there is +12V on both ends.

I just re-read my description and want to make a correction: If the generator/alternator is not charging the battery that blue wire connection is at ground level. If the generator/alternator is charging the battery the blue wire connection becomes +12V and the light goes off.

[ossiblue]

Porwolf is correct about how the light is supposed to work. There is no way the light should be glowing with the ignition switch completely "off". Even if your generator/voltage regulator were faulty and failing to ground at D+ with the engine off, the light would not be on because there is no ground at the ignition switch. The only thing I can see is the light is connected incorrectly at the ignition switch, possibly connected at the power terminal which is hot at all times. If that's the case, the light would be on always because it would be grounded at the gen/vr. When the engine starts and the gen/vr put out voltage, the light goes out, as it should.

Time to check the wiring for the light to the ignition switch, IMO.

Time

[AlexJ]

Hi, I also have the same problem but it started when I accidentally changed the position of the cables when connecting the battery...
The car starts send light goes off...

Does anyone knows what might been burned?

[timmy2]

Reversing the polarity on the battery has been known to damage alternator components.

[AlexJ]

Thanks for the news!

[AlexJ]

What is strange is that light goes off with the engine running...