Stewart Warner Volt Gauge shows no charge (Page 1/2)
altownsend JAN 22, 02:22 PM
1986 Fiero
4-Speed Manual

I have a project car (1986 Fiero) and a previous owner had removed the dash and accessories and installed Stewart Warner gauges (Fuel, Tach, Speedometer, Coolant Temperature, Oil Pressure, Volt Gauge). I have the Tach working. I have not driven the car, so not sure if the speedometer works. I tested the Oil Pressure circuit and found the gauge wire at the dash. With key at the 'On' position with connector on the sensor, the gauge pegs to the far right. With the key to the 'On' position and the wire grounded at the engine, the gauge pegs to the far left. I concluded that the sender is bad and have ordered a replacement. The Temperature gauge is stuck at 190 degrees and pegs to the far left if I unplug the sender wire from the gauge. I can run an ohm meter from the wire (ECM) at the engine and get a response at the temp wire at the gauge.

Now, the Volt gauge. I need help with the Volt gauge at the moment:

I get (with my voltage tester) 12 volts at the battery, at the gauge, and at the alternator. With the engine running, I get 12 volts at the gauge, at the battery, and at the alternator. However, the gauge reads 10 volts when the engine is running, 11 volts when the key is in the 'On' position.

The engine runs as though it is laboring, and it eventually goes from a laboring idle to a stall. Again, measuring voltage at the alternator and battery yields 12 volts and not 13 or 13+ suggesting that the battery is charging. Two days ago, I went out to start the car, and the engine turned over fine three times, and then, the battery was no longer had the CCA to turn the engine. A jump got the engine running, but, no charging, and the gauge still had 10 volts and bottomed out when I turned on loads.

I have cleaned the wiring at the alternator (I still need to unplug and assess the connector on alternator), battery is new. Comments related to a fix, please.
Gall757 JAN 22, 05:22 PM
Do you still have the volts light? It is a necessary part of the alternator circuit.....otherwise the alternator won't charge.
altownsend JAN 22, 06:30 PM
Gall757, good point. And, I have read a lot of posts about this. Now, let's pursue this and confirm the status based on evaluating this light and it's function in my situation:

The Stewart Warner gauge has three (3) posts. I am using the 12 volt switched post and the ground posts. Since I have an after market dash set-up, I do not have the light that you asked about, neither have I identified the wiring to put that bulb in the circuit. So, please help me identify or locate that lighting source (wiring) as it relates to the alternator/charging system or exciting the alternator/charging. I do not have this lighting source at the dash, and have not found what is required to confirm that the wiring is part of the charging circuit. I have a lot of loose wires at the dash (about 8 or 10) that goes nowhere. They were removed or disconnected by a previous owner. So, please instruct me or direct me to the wiring (color, how it is powered, where exactly or how exactly I find the circuit to locate the wiring and where it goes in the circuit). I am confident that I will follow that instruction and affect a fix. Thanks

[This message has been edited by altownsend (edited 01-22-2020).]

Gall757 JAN 22, 07:05 PM
Reading Material.

http://www.fiero.nl/forum/A...060811-2-068806.html
altownsend JAN 22, 09:48 PM
Gall757,

I read the conversation that you referenced. I have two tasks in testing to see if I can find the charging issue:
First) Trace the two connector wires connected to the alternator. I want to confirm where they lead to. I am hopeful that one leads to the dash alternator light, and that I can put that alternator light into the circuit. A previous owner put a dash light in the center of the cluster. With the key at the 'On' position, and the engine running, this light is on constant (it is green). I will trace it's wires to see what device it is communicating.

Secondly) I want to check all of the 12 volt circuits/connections that are destination from the battery (looking for 12 volts on all devices (alternator, lines to and from, starter, and all relays and devices run from 12 volts - from battery)

Thank for your input. Let's team up and solve this one.
Gall757 JAN 22, 10:13 PM

quote
Originally posted by altownsend:

Thank for your input. Let's team up and solve this one.



I may not be that useful.....There are many others with more knowledge that will contribute soon.
If I had this issue, i would wire a lightbulb between the pink/black wire and the brown wire and see if it acts like a volt light.....or if it blows a fuse...

[This message has been edited by Gall757 (edited 01-23-2020).]

altownsend JAN 25, 07:17 PM
Okay,

To date, the tach is working, have not driven the car to check the speedometer, fuel gauge does not work, oil pressure now works, volt gauge now works ( I found the alternator light wire and put a 194 bulb in the circuit. The system now works and the system is charging), temperature gauge does not work.

Next gauge to get working is the temperature gauge:

Troubleshooting to date:

Traced yellow and brown or black wires today (Saturday - January 25) at the temperature connector at the engine. The black or brown wire (it is so dirty that I cannot tell what color it is) has continuity at the dash gauge. It reads 17.5 ohms. I do not understand this and will state why momentarily. The yellow wire can be traced using the ohm meter by slitting the wire between the connector and the ECM. I get .07 ohms on the yellow wire inside the passenger compartment. Again, I have continuity on the dark color wire from the connector at the engine and the dash gauge connection, 17.5 ohms. I cannot pick up continuity on the yellow wire after the ECM.

Difference in continuity on the dark color wire: When I test the ohms between the sensor connector at the engine and the wire inside of the cabin, I get .07 homes. When I test between the cabin to the dash gauge, I get 17.5 ohms.

So, someone, please walk me through the complete temperature gauge circuit, with color of wires, where the wires originate and terminate. The ECM sensor is new.

Background: The temperature gauge was pegged to the right. The incorrect wire was terminated to it at the gauge. I tested with my ohm meter and found the wrong wire problem. I have the dark colored wire (black or dark brown) terminated at the temp gauge. I am getting 17.5 ohms between the engine bay ECM connector and the gauge. But, after confirming continuity between the yellow wire at the connector in the engine bay, and a slice in the cabin before the ECM, I get .07 ohms confirmed. But, again, I cannot pick up continuity on the yellow wire, or any other wire after the ECM (output side - in route to the dash)

Any fix recommendations, please

[This message has been edited by altownsend (edited 01-25-2020).]

olejoedad JAN 26, 12:19 PM
The sending unit for the gage and the HOT light is located on the back (trunk side) head, on the left end below the valve cover, near the tach filter.
It is an odd shaped plug, rectangular with a flag for keying into the sensor.
The wire.colors.are.dark green and dark green with a yellow stripe.

The yellow and black wires and sensor are for the ECU, and located on the belt end of the engine and on the lower intake manifold.
altownsend JAN 26, 02:49 PM
Thank you for the information. I will review and use it to see if I can find my solution.

Now, your description of the wiring near the tach wire on the throttle body side of the engine, can you walk me through the wire trace from there to the temp gauge? I will trace the wire to see if I can find them on the dash side of the harness, however, if you share the wire trace, it will be easier for me to find the temp gauge wires at the gauge cluster.

Question:

With the black wire at the sensor, I am getting continuity between the connector on the sensor side and a wire at the temp gauge. It might be a wrong connection. This is another reason why I asked for the wire trace from the connector that you mentioned at the tach wire side of the engine to the temp gauge.

In summary:
I am getting 17.5 ohms at the temp gauge from the ECM temp sensor.
My wire from the harness at the temp gauge is light gray.
Please walk me through the wire trace from the engine compartment to the temp gauge at the dash - thanks
altownsend JAN 26, 02:51 PM
Also:

I read somewhere last night that a temp light is supposed to be in the circuit. Please comment