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| Temp and fuel gauge issue... (Page 1/2) |
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CSM842M4
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SEP 06, 09:36 PM
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Hello again, all. My wife's '86 SE is exhibiting some concerning behavior; the fuel level gauge reads higher than actual, and the engine temperature gauge never moves off the cold mark. As to the fuel gauge, it reads full when the tank is full, but it shows just under 1/4 when there's not enough fuel in the tank for the pump to pick up. I'm hoping, kind of, that since the gauges are adjacent to one another, that they may share a cause, but I can also see how that would not necessarily be the case. We could probably learn to "dope" reading the fuel level, but I'd really be happier knowing how hot or not the engine is running. I'm aware that both gauges are essentially ohm meters, with the senders providing a variable resistance ground. Anyone have any insight or experience with this? Any/all input that gets me any closer to an answer and fix is greatly appreciated. Thanks in advance - Chris
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PFF AI Bot
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SEP 06, 09:36 PM
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DISCLAIMER: This is an AI generated response. It may produce inaccurate information about people, places, or facts.
Hello Chris, The issues you're experiencing with your '86 SE's fuel and temperature gauges might indeed share a cause. One common issue that can cause both gauges to behave this way in a Pontiac Fiero is a problem with the gauge cluster itself or the wiring connections to the cluster. The temperature gauge staying on the cold mark might be a result of a faulty coolant temperature sender or a damaged wiring/connection issue. As for the fuel gauge, this might again be due to a faulty sender unit or bad ground connection in the circuit. As a remedy, you could try accessing the gauges and making sure all the connections are intact and clean. If you find any corrosion, clean it off. Also check the wire harnesses to these components to ensure they're in good shape and making proper contact. It might be a good idea to replace the coolant temperature sender and fuel sender unit as they are typically inexpensive items. Unfortunately, diagnosing this issue might take some trial and error and a process of elimination, but once you've checked these elements, you'll have a better idea of what might be causing the gauge inaccuracies. Remember to disconnect the battery before diving into any electrical work to prevent shorts! Best of luck with your troubleshooting! Click to see AI response
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Vintage-Nut
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SEP 06, 10:52 PM
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sleek fiero
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SEP 06, 11:10 PM
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Like the ogre says clean and check your connectors and grounds. It doesn't take much corrosion / dirt to add resistance to these circuits to cause a bad reading. sleek
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buddycraigg
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SEP 07, 04:12 AM
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| quote | | Originally posted by PFF AI Bot: |
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Hi PFF AI Bot.
buddycraigg, Nice to meet ja.
Love your perfume.
What is that?
The stench of death?[This message has been edited by buddycraigg (edited 09-07-2023).]
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Vintage-Nut
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SEP 07, 08:37 AM
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CSM842M4
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SEP 07, 08:03 PM
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Brief update - I believe I've ruled out the temp sender as the cause for the inop temp gauge: after disconnecting the harness from the sender and twisting the ignition switch to "On", grounding one wire in the connector turned the "hot" light on, grounding the other had no effect on the gauge. Also noticed that with the connector on the sender and the ignition switch "off", the temp gauge needle parks between the "100" and the middle of the scale. Turning the ignition "on" swings the needle to the "100" mark. This is with the engine cold, by the way. I'm led to believe by this behavior that the gauge is okay, and something is going on with the circuit to the sender. Does that circuit make and break through the ignition switch, or through a relay, or some other way, or am I off track here? Does it sound like the gauge is acting correctly, except for not seeing the sending unit? Hope this sparks something with someone here... Thanks again - Chris
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Vintage-Nut
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SEP 07, 11:43 PM
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| quote | Originally posted by CSM842M4
ignition switch to "On", grounding one wire in the connector turned the "hot" light on, grounding the other had no effect on the gauge. |
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When the ignition switch is 'On' and grounding the other sensor wire to the engine (ground) should cause the temp gauge to PEG at full-scale.
If this does not happen then the wiring between the sensor and instrument panel is the problem. Check the connectors at the sensor and the connectors in the back of the gauge panel.
Let me know if this makes any sense to you,
VN
Edit:
The Coolant Temperature Gauge is an 'Ohm Meter'
Full-Scale is 'Ground' or no resistance
Cold is ~1,600 ohms
Read this Coolant Temperature Gauge link of the circuit....
https://www.fierofocus.com/...osails/tempgage.html[This message has been edited by Vintage-Nut (edited 09-08-2023).]
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CSM842M4
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SEP 08, 10:15 AM
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Thanks to all so far! Neat tutorial on the circuit trace rehab, and handy information on the wire swap (and the reason for doing it!). Will absolutely be doing both of those procedures while chasing this down. Does it sound, so far, like the gauge's behavior is normal for an un-modified installation, and that hopefully the gauge is not out of commission? I'm torn on the AI-generated response - it was all useful information, and some of it was new to me. But I will probably always prefer actual intelligence over the artificial variety. Thanks again - Chris
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buddycraigg
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SEP 25, 11:07 PM
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I wanted to clarify that my comment
I was not saying that the AI system is dead.
I think AI is going to take over and the rest of us are dead.
Or at least me, who does tech support over the phone for my job.
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