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I just picked up a 68 coupe, nice car, has a few issues but don't they all. trying to understand the temp gage. I have a problem with something pulling down the battery, the only thing that affected it was pulling the gages fuse. Battery is fine now, prior to pulling the fuse it wore down overnight and needed charged. Prior to pulling the fuse, the temp gage worked fine, it was actually pretty accurate compared to an infrared. Now with the fuse pulled, the only thing I can see that doesn't work is the temp gage. The sensor reads about 1,000 ohms to ground when cold. When i was looking for what was pulling the battery down, I disconnected the battery and put an ohmmeter across the battery cables, the reading I got was that same 1,000 ohms. Shouldn't the temp gage be out of the circuit with the ignition switch in the off position? Any help would be appreciated.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
you are reading across the pos to negative battery cables? you wont get a good reading that way. You are reading thorough the wires, the fusible links the junction at the horn relay, the engine grounds, the voltage regulator...theres way to much in the circuit to do it that way. For one the wiper override will kill your battery if its in the override position. THat is a fact and they have a factory change in the AIM about it. as for your temp gauge, if its factory then it shouldnt cause you an issue unless someone wired it incorrectly. you should get a 68 AIM and a Factory service manual. You can get a good set of colorized wire diagrams off of EBAY that are easy to read. If you want to identify wire ends and plugs get a Doc Rebuild OhSo Ez wiring diagram. THeres one for the engine and one for the cabin. Call and order on the phone, its the easiest way. Get one of there vacuum hose sets as well, they are the correct diameter and fit correctly on the vacuum relay valves. No one elses will. If you didint know there is a lot of 68 only parts, do a couple of searches, there are multiple threads about it...its along list. The steering and radiator cross with 67 parts.
I think your missing something here.
Like a wiring schematic.
On the gauges fuse, could it be that it also powers a number of things you do not see?
things like headlight warning, parking brake light, and power to excite the alternator. Power through the gen light to the alternator? At least on newer C3's. You have a 68, I don't have that schematic. But you should.
Thanks for all the information. I should mention, my wiper door is stuck open, I cant close it with the motor running or not. I'll call docs today and request those diagrams and whatever other manuals i can get from them. I was warned not to get a 68 because of all the unique qualities. It should keep me busy this winter.
We love our 68's, but everything is different on them because GM made so many changes to them. They still have the 327 and 68 Camaros, Nova's and Chevelles had 350's.The wiper motor and it's wiring is completely different than a 69's. In 69 they integrated the voltage regulator into the alternator, so a 68's wiring is way different in that area also. Lou.
bg725
Now that you mention the wiper door it leads me to think that you have a continuously energized wiper door solenoid (located behind the tach). Disconnect and see if your parasitic draw goes away.... I suspect that it will.
If you don't let the wipers complete a cycle on their own and interrupt the wiper start signal by going to off that wiper solenoid stays energized and drains your battery.
Start with that.
Here is a 68 wiring diagram...don't remember where I got it. The wiper issue is an oddball "feature" which can use the search function to find info about.
Originally Posted by bg725
Thanks for all the information. I should mention, my wiper door is stuck open, I cant close it with the motor running or not. I'll call docs today and request those diagrams and whatever other manuals i can get from them. I was warned not to get a 68 because of all the unique qualities. It should keep me busy this winter.
68 temp gage
