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09-17-2021, 03:59 PM | #1 |
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Help With New Instrument Cluster, please
Just installed an new instrument cluster in my 69. The gas gauge reads off to the left side not top center. https://photos.app.goo.gl/EpFhFnFRakxQJBMS9. Just prior to installing I replaced my sending unit with a new one and tested it on my old cluster. It showed half a tank which is about what I have. The new one seems to register but not on the top. It's off to the left. Any ideas would be appreciated. Thank you.
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69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus! |
09-17-2021, 04:06 PM | #2 |
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Re: Help With New Instrument Cluster, please
Did you attach the ground wire to the cluster?
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09-17-2021, 04:15 PM | #3 |
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Re: Help With New Instrument Cluster, please
No I didn't. Where is that located? I didn't recall seeing anything when I took off the old one. Thanks
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69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus! |
09-17-2021, 06:00 PM | #4 |
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Re: Help With New Instrument Cluster, please
Doesn't seem to be a ground wire anywhere that I can see. All the install videos I've looked at don't seem to talk about this. I noted my amp meter ins't working either. All other gauges are good. Any suggestions appreciated.
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69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus! |
09-17-2021, 06:14 PM | #5 |
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Re: Help With New Instrument Cluster, please
Check the original cluster. If I recall correctly will be a wire attached to a post with a bare end. The bare end just went into a clip on the column support or surrounding dash metal.
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09-17-2021, 06:40 PM | #6 |
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Re: Help With New Instrument Cluster, please
There is a picture of the ground wire for the dash in the second post of this thread
http://67-72chevytrucks.com/vboard/s...d.php?t=721429
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09-17-2021, 07:05 PM | #7 |
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Re: Help With New Instrument Cluster, please
Found it. Thank you. The wire is connected as in the thread you referenced.
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69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus! |
09-17-2021, 07:17 PM | #8 |
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Re: Help With New Instrument Cluster, please
I did install the plastic float as per this post http://67-72chevytrucks.com/vboard/s...d.php?t=666161 when I put in the new sending unit but to reiterate, the old gauge showed half a tank as it should have when I tested it. If the float had come off I'd just be getting "E" all the time would I not?
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69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus! |
09-17-2021, 08:57 PM | #9 |
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Re: Help With New Instrument Cluster, please
Did the arm on the float move freely?
I once made the mistake of tightening it a little too much. Outside it seemed to work fine. But inside the tank there was just enough resistance so the arm would get 'stuck' in one position. I originally thought it was a gauge problem until I eventually discovered the real culprit and had to take the sending unit back out. |
09-17-2021, 09:52 PM | #10 |
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Re: Help With New Instrument Cluster, please
Was the old sending unit working properly before you did all this cluster work?? If it's still good, use it to test the gauge. If it isn't good, obtain a known good one or remove the one from your tank. Using a jumper, connect the sending unit "frame" to a good ground.. Connect the brown wire to the post on the sending unit.. Turn on the ignition switch (you can start the engine but it's not necessary).. Slowly swing the float arm through it's range of travel -- 1/4, 1/2, 3/4, and full points.. If the gauge responds but not accurately, you have a problem with the gauge or related circuitry.. If the gauge doesn't respond at all, you probably have a bad gauge, bad connection, or possibly a bad printed circuit..
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09-17-2021, 10:41 PM | #11 | |
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Re: Help With New Instrument Cluster, please
Quote:
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69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus! |
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09-17-2021, 11:06 PM | #12 | |
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Re: Help With New Instrument Cluster, please
Quote:
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69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus! Last edited by Zonaman; 09-18-2021 at 01:44 AM. |
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09-17-2021, 11:14 PM | #13 |
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Re: Help With New Instrument Cluster, please
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09-17-2021, 11:40 PM | #14 | |
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Re: Help With New Instrument Cluster, please
Quote:
The new sending unit registered my fuel level accurately- with the plastic float on the old gauge in the truck. Since it was good on the old cluster I presume it to be good on the new one. That's why I look on the new gauge as the likely culprit. I can pull it and test it just to be sure. I can even put the brass float back on just to be on the safe side
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69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus! |
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09-18-2021, 12:14 AM | #15 |
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Re: Help With New Instrument Cluster, please
I wonder if your tan wire is shorted to ground, possibly where it connects to the sender? I believe that would cause the gauge to point to the left. With the tan wire disconnected from the sender, the gauge should point to the right (3:00).
There's a lot of helpful information in this post: https://67-72chevytrucks.com/vboard/...d.php?t=640615 |
09-18-2021, 12:52 AM | #16 | |
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Re: Help With New Instrument Cluster, please
Quote:
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69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus! |
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09-18-2021, 12:54 AM | #17 |
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Re: Help With New Instrument Cluster, please
Does your new gauge have a resistor installed on the back of it, like in the link I posted above?
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09-18-2021, 01:14 AM | #18 |
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Re: Help With New Instrument Cluster, please
Here's an image of the back of the fuel gauge as it came from the vendor on the cluster. Is that a resistor? I honestly can't tell.
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69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus! |
09-18-2021, 01:18 AM | #19 |
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Re: Help With New Instrument Cluster, please
I agree, it is hard to tell. I am not familiar with reproduction gauges. If there is one, it isn't the same ceramic style that came on these gauges originally. It would be interesting to measure the resistances between the three posts as was done in the troubleshooting guide.
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09-18-2021, 01:30 AM | #20 |
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Re: Help With New Instrument Cluster, please
I have seen a video from LMC explaining that they don't use resisters on modern reproduction gauges. https://www.lmctruck.com/product-vid...el-gauge-video I bought this one from Brothers so I could ask them. Can this test be done with the cluster installed as it is? It's very tight under there and I'm kinda old & fat - nevertheless, I'd rather not have to pull that cluster out unless I wind up returning it. Also, is there a way for me to test that tan wire? I looks as though it goes from the fuel gauge space on the fuse box, under the carpet and to the sender. Have I got that right?
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69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus! Last edited by Zonaman; 09-18-2021 at 01:48 AM. |
09-18-2021, 01:47 AM | #21 |
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Re: Help With New Instrument Cluster, please
I agree it is a major pain to work on anything up underneath the dash.
Did your old gauge cluster have temp/oil/battery gauges on it, or was it the simpler warning light style? The reason I ask is because there are differences in the wiring harness for the two types of gauge clusters. One of the differences is the connector pin that provides power for the fuel gauge. |
09-18-2021, 01:52 AM | #22 | |
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Re: Help With New Instrument Cluster, please
Quote:
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69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus! Last edited by Zonaman; 09-18-2021 at 01:59 AM. |
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09-18-2021, 01:58 AM | #23 |
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Re: Help With New Instrument Cluster, please
Running through the tests outlined in that LMC video should help you pinpoint the problem. If you've got test leads with alligator clips, then you should be able to fasten them to the gaige posts and then do all the tests while sitting on the seat. Unplug the big black connector from the back of the cluster to isolate it from the truck during the tests.
Is your Cluster Feed fuse still good? |
09-18-2021, 02:13 AM | #24 |
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Re: Help With New Instrument Cluster, please
I get continuity across it.
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69 C-10 LWB, 350, 700r4, 3.73 posi-traction, front disc brakes. Built for the desert- She can take the heat! Vivat Rex Chevus! |
09-18-2021, 02:18 AM | #25 |
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Re: Help With New Instrument Cluster, please
If it were me, the next thing I would do would be to verify the presence of 12 volts across the power and ground posts on the gauge with the key in the run position. I would also make sure there isn't continuity between the input post (connects to tan wire) and ground.
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