Temperature gauge is erratic
 

Good Morning!

I seem to be having a erratic temperature gauge issue.
When driving or parked gauge is erratic. It's especially noticeable when over 2000 RPM. Sometimes I also see a spike in the speedometer but its only for a quick second and barely catches my eye. Two weeks ago I replaced the ECU due to a bad capacitor.


-I checked the G101 ground, engine ground, and chassis ground. All look well

-Temperature is normal, fans turn on normal, and thermostat was replaced with OEM in January. Testing temps is done with an IR temp gun.

I was thinking it could be the igniter in the distributor, bad regulator in the alternator, or a open short in a wire somewhere. Alternator was replaced 2 years ago along with starter and battery was replaced 3 months ago.

Made a quick vid:


Any suggestions will be helpful!

I think your problem is somewhere in the gauge cluster. It is a bit of work to remove the cluster. I'd pull the cluster, take apart, and look for corrosion where the gauges connect to the main board. Also look for corrosion on the main board where the wire harness connects on all components & solder joints.

There are also some grounds (G402 and G404) that you may want to clean. The common diy thread has links to sites with online shop manuals. The 94 accord is identical to the 95 and will help you out with how to remove the cluster, ground locations, etc.

I'd also inspect the wire coming off the temp sender (one pin sender) on the end of the head under the dist.

That sender "varies" resistance to ground as the temp get higher - full ground when hot.

Thanks for the info guys and I will check the temp sender this evening.

Here are some pics of the circuit board, think some of the solder joints need to be touched up?

I have completed the following:

-Cleaned G201, G301, G2, and G101
-Replaced alternator (I have a spare)
-Unplugged temperature sensor and grounded with ignition on, gauge shot to hot.
-Resoldered all points on the instrument cluster that appeared to look suspect to me. All wires in the harness looked normal, no breaks.

Unsure on what next to check.

In your video, the temperature at idle before you rev the engine is high. Normal operating temperature is about 1/4 to 1/3 up the scale.

Since you grounded the wire and got a response from the gauge in the car, I'd test the ECT sensor. Unplug the sensor, connect your volt meter red lead to the sensor post, then connect you black meter lead to ground. Measure the resistance on the sensor when the engine is cold and should be around 140 ohms. Run the engine till you are at normal operating temperature and resistance should be around 40 ohms. When you rev the engine, see if the resistance drops close to zero or bounces around.

Thanks for the response and help. The temps in the car general are 1/2 before the half mark, I just happened to catch it bouncing around on the video.

Tested the resistance with the engine cold and it was 574 ohms. I know that's way out of spec. Started the car and let it run till both fans turned on and off twice and measured the resistance. It dropped between 37 - 28 ohms with the engine still running. Revved the engine a couple of times and it went south from there until negative numbers were showing. At one point it was -40 ohms, so I suspect the sensor is bad. Grabbed a bunch of the sensors at the pull-a-parts yard and will swap my current for another sensor. Also will burp the system since antifreeze will leak once I swap the sensor and report back.

Hopefully it is just the sensor and not a real reading from the coolant.

Solved!

It was the sensor. Replaced sensor and burped the coolant and took the car on a 30-mile drive and erratic temperature gauge. Thanks PAHonda and poorman212!

My gauge is doing the exact same thing. Its wobbling all over the place I replaced the coolant sensor and its still fluctuating. I am going to bleed/burp the system tonight and hope that works. Any other ideas on why it might be doing this? Or did you do anything else to solve the problem or could it be the whole cluster?