Westland

After using the appropriate OBD2 scanner I discovered that ABS codes don't necessarily reset once a correction is made. For example, it held the code for when I disconnected the front left speed sensor during troubleshooting. The underlining code for the new hub/sensor: C0040 - Right front wheel speed sensor circuit. DTC Status: Signal Erratic C0040 - Right front wheel speed sensor circuit. DTC Status: Incorrect Component Installed After resetting the codes, all went away except the above. I reconnected the original sensor and reset the codes again. No codes now. Hopefully resolved.

2018 2WD 1500 5.3l After replacing the front right wheel hub assembly I now have a service stabilitrak alert. ABS/ stabilitrak icons are illuminated. I went for a brief test drive, 1 - 2 miles and ride, all was smooth besides the code(s). My current OBD2 doesn't read ABS so I tried the following: Disconnect battery for 5 minutes Disconnected wheel speed sensor (new sensor included with hub assembly), QD cleaned plugs and reconnected Unplugged and reconnected both front sensors Plugged in the old sensor (still in the old hub) I did not drop, beat or damage the new hub assembly. I will have an OBD2 reader tomorrow that will give the code(s) for ABS. Till then, has anyone come across this?

Rare bird

Pumping the brakes momentarily relieves the problem? When the problem begins does the truck pull to one side? Have you felt the rims to see if one or more is hotter than the others?

Yes the fans were in fact bad. The truck has been cooling properly.

My 2014's instrument cluster has started to systematically lose LED lights on its board. It began with a dark area in the speedometer and then progressed to the tachometer. The PRNDL "P" stopped illuminating white but would illuminate red when selected. Now more of the PRNDL lights have stopped working. After a few months now I cannot see either the tach, speedometer, temp, or fuel gauges at night. Anyone else experiencing this? Truck has over 170K miles.

My temp sensor ohm'd out within range (80F - 2500 ohms). Got a new thermostat and replaced. I could blow through the old thermostat housing and thermostat itself was visibly cocked. Thank goodness these fail open rather than closed. I removed the negative battery cable for a moment to reset things and fired it up. Problem solved. A little concerned that the previous thermostat was just over a year old though. The thermostat with housing was around $50. Hope this helps your issue.

Are your fans running?

While I have the 5.3, I have had this issue before and have it again today. Usually this is the case... If the engine temp does not reach a particular temp within an allotted time after start up, it will command the fans to run on high. This leads to two possibilities. The temp sensor is faulty or the thermostat is stuck open. Last time my truck did this it was my thermostat. You can test the temp sensor without pulling it from the engine. You'll need a multi meter, remove its plug and test resistance across its leads. My trucks temp gauge shows the increasing temp until suddenly the needle drops to 0 and the fans turn on. This does not rule out the sensor however. Awhile back I found a site that has some basic values for what resistance the sensor should read and it ruled out my sensor. Below is a link to it. It is possible it isn't reading correctly for me this time. I plan on checking resistance once the engine cools down. https://troubleshootmyvehicle.com/gm/4.3L-5.0L-5.7L/how-to-test-the-coolant-temp-sensor-1 If you've replaced this sensor twice then most signs point to the thermostat. However, the AC pressure sensor will also cause the fans to run high if it has failed. I haven't read of it happening often.

I put the new $600 fan assembly in the truck. Cranked it up and cycled the AC. Fans did not turn on. Almost cried. Then the fans turned on. Almost cried again. Problem solved on this one. Thank you all for the input!

While you're waiting on getting the code... Does the truck vibrate/ shutter at low speeds while stopping? Pulsing brakes? Do you notice higher RPM's at speed? Does it pull to one side or the other at any speed while applying the brakes? Do you feel vibrations more in one area than another? ie Steering wheel, seats, floor? See if you we can rule out suspension and the brake system.

What code is it exactly? A bad injector will cause misfires that in-turn add to vibrations. How long has the code been showing compared to the vibrations? Is the code intermittent?

Diagram showed the signal wire is accessible in a plug between the ECM and fans. It is located next to the under-hood fuse block where the second battery tray sits. It has 3 wires. One is fan signal and the other two are for the ambient air temp sensor. I decided to take the harness out of the picture and jump ground/power (from battery) and signal directly to the left fan. The fan repeated what it was doing from the beginning. It bumps a couple times and then tries to spin up but stops after it almost reaches low speed. That repeats after a minute or so. The right fan does nothing when jumped the same way. So this should rule out the fan plugs/ harness/ grounds (all cleaned) and ECM signal. Again I still find it hard to believe both fans failed together. It is possible that one fan fails and it makes no significant difference in engine temp. Then later the second fails. Local temps have been 90-95F. Engine temp sensor, AC pressure sensor both show to command the fans on/off. Transmission fluid temp sensor might but I haven't seen it in any diagrams. Still open to input. Engine has 170K miles btw.

Knowing now that direct current alone will not excite the fan motors, does anyone know of a sensor that would influence the ECM to command them on/off aside from the temp sensor? Could this be an ECM issue? Cooling Fans (Radiator Cooling Fan) - ALLDATA diy.pdf

Didn't cross my mind. Yep, they are controlled with a PWM signal from a controller. Good info, thank you! I'm really missing the fan clutch right now.

I've been using alldata and its been amazing. AC has been working fine but I went ahead and put my manifold gauge on it to see. Checks out fine and the compressor turns on as well. Alldata showed me the fan wiring diagram and it would seem the relay/control is handled by the ECM. 1 Wire leaves the ECM and branches to both fans. Each fan has a always hot 12v coming from the underhood fuse box. Then of course the ground coming from the frame on each side. Thank you for the idea though!

I'm not ready to spend the $ for the hptuners scan tool. I suspected a ground issue so I located the exact grounds per fan on the frame. Each fan has its own ground location on either side of the front frame of the truck. I cleaned those up but no joy. I cleaned the ECM ground that is located on the left side of the engine down by the power steering pump. No Joy. I was able to pull the connectors from the fans and each fan has 3 leads; Pin 1 - GND, Pin 2 - B+12v always on (from fuse), Pin 3 - not used/available, Pin 4 - Signal from ECM. Hooked up jumpers to ground and applied 12v to Pin 2. No spin on either. I then added another jumper to Pin 4 and applied 12v to it at the same time. No Spin. So either I'm using too small of a gauge jumper wire set, not applying voltage correctly or the fans are both in fact bad. Going to get some new fans coming while I keep thinking of ideas outside of that. Still entertaining anyone with thoughts on it. Will update.

2014 5.3l. The truck will not overheat while driving which tells me the water pump and thermostat are functioning. Temp sensor is sending because my gauge registers and my OBDII device reads comparatively. Coolant level is correct. The AC runs warm while at idle (compressor running and system properly charged). At speed AC blows colder due to forced air over the condenser. I notice the driver side fan slowly spin up for only a few seconds before it then stops. It then waits for a minute or two more before doing the same thing. Both fan fuses (40A) are good. 12v at the fuses. There is not a conventional fan relay located in the engine bay fuse box. Nor is there one in the other two fuse panels. All fuses on all boards are good. Obviously I'm at a loss. I can't manage to directly test the fans due to the wonderful electrical plug design. Some strange long white plastic stick in place next to the plug of which I cant see well to dislodge. I find it hard to believe that suddenly both fans fail in unison. Does anyone have an idea of what may be causing this no-fan issue?

I had this issue with my 2014 5.3l WT. My thermostat failed and stuck open (not like the old days). If the engine does not reach a predetermined temp in a set time after start up, the fans will kick on high as a safety. New thermostat fixed the problem. Also a faulty temp sensor that sits right next to the thermostat can cause this issue.