1998 Ford Explorer XLT 4.0, 2WD, Temperature Hand in Dash Inoperative

This 1998 Ford Explorer XLT 4.0, 2WD, came into the shop for a No Crank Concern. Once we found the issue there (a faulty Drive Belt Tensioner not allowing the Alternator to charge), we let the vehicle run to check the charge and the new battery we had installed.

As we let the vehicle run, we noticed the temperature hand in the dash was inoperative. The vehicle had reached normal operating temperature (after running for several minutes) but the hand was still below the "C" on the Temp gauge in the dash.

Below is a picture of the inoperative temp hand with the vehicle at normal operating temperature. The hand has obviously not moved and thus is inoperative for some reason.

The customer wanted us to find and fix the problem.

First, we needed to do some testing to see if it was the gauge in the dash that was faulty, the circuitry or the sensor under the hood. In order to see which it was, we had to disconnect the temp sensor. It is located in the thermostat housing (black plastic assembly).

With it unplugged, I jumped the the circuit to Battery (-). In the picture below you can see my jumper wire connected at the negative battery post on the battery.

Next, I put a probe gently into the connector for the temp sensor, so as to jump the circuit. If the circuitry (the wiring) from the connector to the gauge was good . . . and, if the gauge in the dash itself was good, this test would prove that because the hand in the dash should move all the way to the "H" position or even a little past.

In the next pic is a shot of the probe placed gently in the connector and the jumper wire connected to it.

The word gently is important here. The probe should never be forced or jammed into the connector. This could ruin that terminal of the connector.

Now, with the circuit jumped, we looked at the dash to see if the hand had moved or not. Below you will see the evidence.

Now we saw that the temp hand had moved all the way past the "H" mark on the gauge. This told us two valuable things: first, the circuitry (wiring) from the temp sensor connector all the way to the gauge was good; and second, the gauge in the dash was also good.

This one simple test ruled out two of the three possibilities and left us with the conclusion that the temp sensor was faulty and needed replacing. After replacing the sensor (we actually had to replace the entire t-stat housing because the sensor could not be removed from the housing: the boss (threads) had come loose and was turning with the sensor. I have another post about replacing the t-stat housing on a Mustang) the gauge in the dash now worked as it was designed to do.

We filled the coolant system up with coolant and gave it a test drive.

In the picture below is the temp hand operating normally with the vehicle running at normal operating temperature.

Another job was completed and we shipped the vehicle. The test was quick and easy and saved us a lot of time from guessing at what "might be" wrong to find what "definitely" was wrong. This is why the old adage says, Test . . . don't guess!

2003 Ford Explorer XLT 4.0, Clicking Noise in the Dash When Operating the HVAC System

This 2003 Ford Explorer XLT 4.0 came into the shop with a customer concern of a clicking noise in the center o,f the dash when he attempted to change the temperature from cold to hot. This vehicle has a manual HVAC control system. If he just barely moved the temperature knob, the noise would start. If he had the vehicle running and had the temp knob all the way to heat, the noise became louder.

This post is not so much a "how to", but rather a "why" post. It is not necessary to remove the entire dash to do this job; though, the service manuals call for that. I have found the job can be done by removing he center console and the cover beneath the steering column.

The issue is a common one on the Explorers around this year model. The culprit is a faulty temperature blend door actuator. Below is a picture of the actuator.

Internally, this actuator is made up of two small plastic gears. The piece that fails the majority of the time, causing this customer concern, is the smaller, black gear. If you take the actuator apart to see inside, you will see that this black gear has anywhere from two to three teeth sheered off of it. Below you will see the inside of the actuator and the black, plastic gear with the missing teeth.

Below is the small gear by itself. It may be hard to see, but in the pictures below, the two sheered teeth are at approximately the one o'clock position.

These missing teeth cause the gears to slip, not allowing the actuator to move the blend door to its proper location. When the gears hit this bare spot (the spot of the sheered off teeth) it cannot catch and so slips, causing the clicking noise in the dash.

We removed the faulty actuator and replaced it with a new OE actuator. We then tested the system, moving the temp knob from cold to warm and back several times. The noise was now gone and the blend door was operating properly.

1994 Ford Taurus Wagon 3.8, Cooling Fan and Fuel Pump Run Continuously With Key in On Position

It's been a while since I've been able to post.  I have several to post and I'll start with this one.  This is a 1994 Ford Taurus Wagon with the 3.8.  The customer brought it in after working on it himself since before Christmas.  Basically, after many repairs and swapping parts, the original concern was still present.  He gave me a list of all the parts he had replaced:  fuel pump, fuel pressure regulator, ECM, CCRM, Coolant Temp, Ignition Switch . . . etc.  He had tested the grounds several times and had found no problem.

The symptoms were when he would turn the key on, the cooling fan would come on immediately and the fuel pump would run continuously and not cycle after two seconds, and he could not get his code reader to communicate with the ECM.  From that description, I felt something was going on with the grounds: either with the ECM or its contacts or a ground on the vehicle.

I knew from other repairs a common problem on these was the ground connector located between the battery and the radiator.  Often times, when you unplug this connector (a two wire connector) it will be corroded.  When I unplugged this one I saw no corrosion.

However, to be sure I jumpered the two wires (harness side) straight to the negative battery post.  When I turned the key to the on position, the cooling fan did not engage and the fuel pump primed for two seconds and shut off.  Also, my diagnostic machine would now communicate.  Presto!

I tested it some twenty times or so and each time it worked as designed.

I spliced two good wires together and drilled a new ground contact on the body and put loom around it.

 I again tested it several times and each time it worked properly.

Here is a look at the orignal connector.

Apparently, the wiring on the ground side (in the picture the longer wires) was faulty and not allowing the ECM to have a good ground; hence, the running of the cooling fan and the fuel pump without cycling off after its prime.

Again, sometimes it's the small things that make a big difference.  After telling the customer of the repair, he told me he had probably unplugged and plugged in that connector numerous times.  It did look okay, but upon testing it was faulty.