Temperature gauge sensor

Hi,

I put in a new temperature gauge sensor because my temperature gauge was not working. It fixed the problem for a month. Now the gauge is not working again. What happened ?

Lou

 

https://youtu.be/VVJSwEakRto

I ended up cleaning my gauge cluster off like he shows. Worked for me, but he shows several diagnostic methods.

 

Any luck?

 

Did you make sure the temperature sender is working?

It's a single wire sensor that simply tells the dummy gauge where to sit.

 

So far this is where I'm at. I've seen that video before and it's very informative. I found out that there are two temperature sending units in this engine. This it the 2.4 version. The one near the front is easy to replace and is called the temperature sender. This is the single wire unit. I bought a new one of those and also had to buy a new cap since the original crumbled apart. When I did that the gauge was moving and it moved to just below the middle mark. Then one day it did not do anything. The video describes the same event. His solutiuon in the video is to change that rear temp sensor. Called a sensor since it's the one sending something to the ECU. It's a multi wire plug.

Along about this time my engine light comes on. I buy a blue tooth OBDII and it tells me I have a problem with my IDLE Control System.

I need to change out that fuel filter that's under the intake manifold. I need to clean the Throttle Body and the Idle Control Valve. I'm also replacing the Throttle Position Sensor. The sensor is sending a signal to the ECU. Considering all that might be causing the issue and the need to replace the fuel filter, I might as well remove all those parts and clean them up. Not a big deal if all the nuts are willing to be pursuaded to come loose.

I'm not going to have a better opportunity to get to that temp sensor in the back so that's on the list of things to do as well.

I've also replaced the right front caliper and need to do the same for the Driver side.

Sooooo. I'm waiting for some gaskets for the intake manifold. As soon as they arrive I can jump on this thing in the morning and hopefully have it all done a couple of hours.

I'm not disappointed or discourgaged by the parts needed. It has been sitting for 5 years and these things are to be expected. Nothing that is so expensive it requires winning the lottery to fix it. It's always the labor anyway. Car is easy to work on which is a big plus.

Thanks for asking,

Lou

 

Update,

I finally decided to attack that Temperature sensor in the back of the engine. The way I did it was to first pull the wiring harness that's in the black plastic enclosure that runs along the top of the engine off the clips that hold it in place. I also removed the steel crossover tube to the Air Throttle Body. There are a couple more clips along the cylinder head that hold the harness that need to be loosened. Then you can wire that harness up and over forward out of the way. There's also a steel clip in the back that holds that harness that you can remove to open that access opening to the sensor. The idea being, to get your hands and tools down in there. Once you clear the passageway you can see the sensor. It sits at about a 45 degree angle to the passenger side. You need to get your hands down in there to pull that wiring clip since it locks onto the sensor. Then I used a 19mm deep socket with a swivel and an extension. Pulled the old one and put the new one in. Put it all back together and no change. Gauge still does not move.

I read more about the sender and the sensor and it seems the sender is the one that produces the movement of the gauge. There is a lot of conflicting info out there about how that operates using two temperature devices. My best guess is the computer sensor tells the sender what to send to the gauge. Just a guess.

I also read that if you remove the sender wire ( the single wire) and then rig it up so you can short it to the engine , then go sit and turn on the ignition, the gauge should swing up to the hot side. Which means the sender is bad and the gauge is good. I did that after replacing the sender with a new one and the gauge does nothing. Which, according to those instructions means the gauge is bad. It's all very depressing to say the least. All the more aggrivating since I changed out that sender last month and the gauge was working. Or so I thought. Raised up to the middle than dropped back down when the engine cooled. Then one day, it decided not to move.

I just don't understand what happened. Why did the gauge suddenly crap out. Anyway you look at it , it's going to be a real chore fixing that gauge. Whether it's rebuilding it or replacing it. And why do I have this gutt feeling that it still won't resolve the issue. How do gauges end up on the brink of not working. Anyway, that's where I'm at now.

Lou

 

Here's a follow up on my Temperature Gauge not working. After changing out the Temperature sender and the Temperature sensor and the Temperature Gauge still not working , it was generally agreed that the gauge must be at fault. Rather than trying to fix the gauge I decided to upgrade my gauge cluster with one with a Tachometer. I found a refurbished Cluster on Ebay from a place called Tanin Auto Electronix.

Then I used that link in this thread to find another of his video's that showed step by step what pieces need to be removed sequentially to get to the Cluster. Pulled the old cluster and put the new one in. It's an understatement to say it was great to see the Temp gauge move. Everything now works. Cross my fingers. Here's a couple of shots of the work. It really goes pretty quick.

Lou

 

I wish I read this tread earlier. The temperature gauge is connected to the front sensor only (sender). The rear is connected to ECU only. Changing the rear sensor was a waste of time and money (like you already know ). The video shows 3.4 V6 engine, and in this engine the "sender" is in the back. The guy on the video was replacing "sender" only (the same what you have in front of your 2.4 engine). This is probably where the confusion came from.

 

I listerned to the attached video in this link. I thought he said that he changed out the sender and it worked for a while and then it stopped working. That's when he changed out the Temperature sensor in the back. Then I guess that didn't fix it so he changed out the gauge. That's basically my sequence too. I can't say if it was a waste of time to change out the sensor in the back since I put a new one in and I can't test to see if a faulty sensor would effect the Temp Gauge. As long as you know you have a good working temp gauge. The parts are cheaper than the testing tools. So just replace each one by process of elimination. To prove that the rear sensor is not needed disconnect it.

 

I bet my balls, that the rear sensor (the one with two wires connected to ECU) has nothing to do with temperature gauge on the dash. There are completely separate circuits, and completely different purpose. The same applies to 2.7 and 3.4 engines in 1st gen Tacoma.

What I'm saying, you can disconnect the sender on front (one wire) and the truck will drive like nothing happened just the gauge will never move. Disconnect the sensor on the back and the gauge will not be affected at all, but the engine will run like crap and soon you will have engine check light on the dash.

Look at this like clutch and brakes - two independent circuits, even each one has a fluid, master and slave cylinders and pedals look alike placed next to each other.

And the diagnostics in that case is not a matter of tools, but knowledge of the system.

 

I'm dealing with a similar problem. My Temp gauge works as it supposed to,but I have a code P0115. Plugged in my scan tool & checked the live data. It's reading -40 degrees & the signal is a flatline at -40. The factory manual troubleshooting for this reads that a -40 means that the circuit is open somewhere. Gotta pull the sensor & start testing connections. Hope it's not the ECM. That would suck.