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Temp Gauge not working

Bross82

Bross82

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Spencer, MA
I have an Autometer Pro-Comp Temp gauge in a 1985 K5 Blazer. All the gauges are aftermarket Autometer gauges now and do not use the printed circuit anymore. The temp gauge recently stopped working. When I turn the key, the needle moves up diagonally across the last zero of the 100 labeled on the gauge. But, it never moves up or down besides this. Does this sound like a bad ground, the sender, or is the gauge is bad? Anyone know where to look besides the wiring and the gauge in the dash?

Thanks,
Matt
 
Sorry, I think I left out that all of the gauges except the oil pressure gauge are still electrical. But, the gauges would not fit in the stock dash with the plastic backing and still using the printed circuit. So, all of the gauges (except the oil pressure gauge) are wired directly to the wiring that connected to the printed circuit.
I don't remember anything referring to a different sender being needed for the electrical gauge when I originally bought and installed the gauge. Also, I only see a "1/2'' fitting & 12' tubing included" for the mechanical gauge on autometer's website. I think this is hopefully just a misunderstanding. My fault for not specifying the new gauge is electrical.

As far as the gauges. I believe they all worked when I installed them a while back. My truck had been sitting a long time after and I ran into issues getting it started back up. Within the past few weeks I replaced the carburetor and managed to get it running again. But, when I turn the key, the needle on the temp gauge moves up diagonally across the last zero of the 100 labeled on the gauge. But, it never moves up or down besides this. However, the other electrical gauges do currently work (Voltmeter, Fuel Level).

I checked the wiring in the dash to the gauge. It goes, the wiring comes out from the plastic protector tube that houses all the dash wiring. Each individual wire connects to new individual wires that then connect directly to the gauge, bypassing the printed circuit that used to be there. These and the connections between the wires and the wires to the gauge look good.

Hopefully this explained it better. I am at a loss as where to check beyond the dash if you or anyone has any advice on where to look?

Thanks again,
Matt
 
You must install an Autometer sender with an Autometer gauge you cannot use the factory sender. This is direct from Autometers website.

http://autometer.com/tech_faq_answer.aspx?sid=1&qid=2

Do I need a sender for my electrical gauge?

Electrical temperature and pressure gauges require the use of a sender matched for the type of gauge in use; the stock sender will only work with the stock gauges. Auto Meter gauges are designed to work with the Auto Meter sender that is included with the gauge. Extra senders are available; check out our Accessories.
 
In addition the sending unit I got with mine used a ring terminal that prevents the wire from getting disconnected. I know that my AM temp gauge had the sending unit with it, I just had to do the wiring. I never trusted the original wiring anyway, so it was a good time to bypass it.
 
Hmm.. I don't remember getting a sender with the gauge originally. But, looks like I'll be ordering one now. Thanks.
 
Ok, I have the sender now. But, where is this located? I see what looks like a vacuum line going into the intake behind the carb and the oil pressure gauge line. Am I overlooking it someplace?

1985 K5 Blazer with a 305
 
Water temp gauge sender location is the driver side head between the #1 and #3 spark plugs.
 
Ok. I replaced the sending unit and ran a new wire from the sending unit to the gauge. The gauge was giving me a reading. But, it kept going up beyond 195 after gradually building up over a few minutes. I shut it down. I ended up replacing the thermostat with another 195 degree gauge. I was thinking maybe the other one was sticking from the truck sitting so long. Started it back up, again, the temp gauge gradually ran up past 195 to about 210-215 before I turned it off. It has been a while so I don't remember exactly what the operating temp ought to be. Shouldn't it get to about 195, maybe a little higher, then the thermostat opens more and the temp drops a few degrees? Any idea what the operating temp should be for a stock 305 and why it is giving me a higher reading?

Matt
 
With a 195 t-stat the gauge should read close to 195 but running closer to 200-210 is common.
 
Yep, on mine, with a 350 and a 195 thermostat, I generally show around 200-205 while driving. It will also normally climb a bit higher the first time it warms up, then drop down swiftly, then maintain that temp.
 
Sounds normal.

Don't worry too much about the water boiling. In a pressurized system, water boils at a higher temp than 212 (even more so with coolant).
 
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