Ok, I have been having this problem with my temp gauge in my cluster. The car is a 99 civic with a gsr swap. Lately when I have been driving, the temp gauge will start to creep up past normal. When I come to an idle, it will either go back to normal or keep going up. Also, when I turn my parking lights/headlights on, the temp needle jumps like another 1/4 way up, and if I turn my lights off it will jump right back down to where it was.

The engine bay feels like it is hotter than it used to be (last year with different swap), the fan kicks on. Not losing or leaking any coolant. What would cause my temp gauge needle to jump with the lights getting turned on, and go up and down at random when im driving. Also sometimes the needle jumps with the bass from the stereo.

 

It might be your alternator going bad, check your thermostat also.

 

Alternator going bad would cause my temp gauge to rise and jump? My lights do not dim or anything at all. Thermostat will be changed tomorrow, but I have a feeling its something else since it fluctuates quite a bit when I turn my lights on.

 

The signal for engine coolant temperature in the dash gauge comes from the 1-wire sending unit located below the distributor. Inspect the connector and wire for damage or contamination that might be causing a short.

 

Thank you! I will go take a look at that later.

 

it does not sound like a overheating issue. It sounds like either a sending issue which RonJ@HT already pointed out. It could also be the cluster, if you have a buddy swap clusters and see if the problem still happens, but i would't count on it, because it sounds like a sending issue.

 

I went driving for an hour without my stereo/sub on and everything was perfect, even with turning the lights on/off, everything worked properly. But as soon as I turn my stereo/sub on, is when this starts happening. The temp gauge starts going up, than down, and when I turn the lights on/off it makes the needle jump.

What would cause my stereo to do this to the temp gauge?

 

Check the ground wires.

 

What's up buddy lol. It's Ryan.

Free bump for you. Hope you get it figured out.

 

funny thing is when i had my del sol my temp gauge did the same thing i guess the previous owner rewired the whole car his way so i didnt know what wire was to what but as soon as my light when on my temp an speedometer when crazy everytime i turn...lol so i ended up selling it

 

I had the same problem. I change out the sending unit. Now my car does not overheat. see if that works.

 

I have a few heads laying around and hopefully they have good sensors. I will give that a shot today.

 

hope so too, this **** is giving me a fuking headache

 

Yesterday night was quite cool, it is like 20 degrees hotter today atleast, now that i notice, it kind of seems like its happening when its really hot out. Yet still fluctuates with the lights, and at random it jumps and drops even with the radio off and those ground wires not conected.

There have been times when the bass was so loud the temp gauge needle would bounce with the bass when it hits, could this have messed up the temp needle at all? That is when I started to notice the problem.

 

You really need to check out the sensor

RonJ@HT: engine coolant temperature

 

The ECT sensor sends temp signals to the ECU not to the dash gauge.

 

He doesn't have the stock cluster. Would that change anything at all in his search to fix this issue?

 

No because the sending unit sends it to the cluster, im still running an oem cluster.

I will be replacing the sending unit, temp gauge and fan switch as well as triple checking my grounds again. Will get back with the results later.

 

With the reaction to and the lights and bass I'd go with a faulty ground. Try running another good ground to the engine and see if that helps. And if you've had the cluster out make sure that all of you connections are clean and tight.

 

Speaking of grounds, the ground from the battery to frame is really corroded in the wire loom. Also I do not have a ground from the valve cover to the frame. Would that cause this huge mess?

Either way I will be finding a ground wire for the valve cover to frame, and put that on this evening.

 

Corrosion on the ground is bad news. A bad ground can cause all kinds of problems

 

Yes it was on an old battery before I put a new engine, replaced the battery but cleaned up the wire the best i could, and when you cut the rubber away from the ground wire, it is still built up with corrosion in there. But just bought a new cable for that so will be putting that on with the valve cover ground this evening.

As I just ran up to the parts store for a few minutes to grab that cable, the temp gauge just kept going high almost near the H. Got home, left it running, popped the hood but the fan wasnt on??

So im going to eat dinner, grab a few beers and start replacing the grounds and sensors, and cross my fingers. Thanks for all the help everyone, will be back in a few hours with the results.

 

Well replaced the ect gauge sending unit with one from another head I had laying around, and replaced the fan switch at the same time. I managed to lose quite a bit of coolant when I pulled each of those sensors off, so once I installed the sensors I started it up and started adding new 50/50 antifreeze.

While I was adding slowly, I noticed air bubbles coming up and popping, and I know you are supposed to bleed the system, so I let it go through 3 or 4 fan cycles and kept adding coolant a needed. Eventually it quit bubbling, and I put the cap on and went for a drive. Drove for over an hour and had not one issue.

Before with this problem, my engine bay temeratures were extremely hot, I couldnt even touch the intake manifold witout getting severely burned. Today after an hour of driving and than popping the hood, everything was much cooler and could actually touch the hood or intake manifold without getting burned.

So with the new(used) sensors, thermostat, bleeding the system through a few fan cycles, everything seems to work.

Although, the temperature has dropped quite a bit now that it is evening, and hope this problem will not come back with the hot heat tomorrow.

Well thanks for the help everyone, hope this thread can help others, and if the problem comes back when it gets hot outside again, I will be right back in this thread

 

Hope it works out today. Another 90+ day sucks *** lol.

 

sounds like you had air in the system the whole time. as the air was cycling through, the thermostat and gauge sensor may not have been functioning properly causing intermitent overheating or false readings. same thing happened to me after an intake install, forgot to bleed the coolant and the gauge was freaking out. glad to see its fixed.