Drive-train service light on

BRAINSY

MEMBER
2010 FORD EXPLORER
4.6L
4WD
AUTOMATIC
156,000 MILES

A yellow wrench light comes on about every third time I drive my SUV. I suspect that this is related to a recent problem when the same wrench light came on but was red with the message "SERVICE RSC NOW", along with an audible alarm, and the trans shifted itself into 3rd gear and stayed there until I restarted the vehicle (there was a loose connector located in the console). I took it back to the dealer and there are no codes stored. The light goes out if I press the reset button or if I turn off ignition. I will try taking it to the shop and have the codes read while the vehicle is running and the light is on. I might add that this all began shortly after I had the transmission serviced. I'm wondering if it could be as simple as transmission fluid level too high or too low.

Thursday, May 28th, 2020 AT 2:18 PM

5 Replies

JACOBANDNICKOLAS

MECHANIC
110,176 POSTS

Hi,

I don't feel the transmission fluid is the cause. The only way to be sure is to scan the computer CAN system. However, there is a self test you can try. Follow these directions and let me know what you find. This should indicate if there is a fault in the instrument panel.

______________________________

IC Dealer Test Mode

To enter the IC dealer test mode with the engine off, press and hold the SELECT/RESET button (base IC ) or the message center RESET button (message center IC ). Turn the ignition switch to the ON position and hold the button for approximately 3 to 5 seconds. Release the button and press the reset button one time to display ENGINEERING TEST MODE. Press the reset button once to advance to each stage of the self-test. The information from this mode is displayed in the odometer display. All gauges and lamps will operate normally during this test mode unless otherwise noted.

To exit the IC self-test mode, turn the ignition to the OFF position.

________________________________

Next, because of the vehicle's design, the CAN system really should be scanned. CAN stands for computer area network. This is how all the modules communicate with each other. By performing a scan of the CAN system, it should point you in the correct direction of where the fault is happening. Here is a link that explains how this is done:

https://youtu.be/InIlnsjOVFA

Let me know what you find or if any of this helps.

Take care,
Joe

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Thursday, May 28th, 2020 AT 8:19 PM

BRAINSY

MEMBER
6 POSTS

Hi Joe,

Thanks for your response to my question.
As you suggested I performed the I/C self-test and could not see anything that looked like a problem. I noted that one of the displays I scrolled through said "NO DTCs LOGGED".

Part of the mechanic's diagnosis was what he called a "deep scan" which told him that the vehicle's computers are all communicating properly with one another, and that there are no DTCs. And I tried my own OBD2 device and it tells me the same.

Finally, in case it matters, since I last wrote I have driven the vehicle on two short trips, both times the SERVICE DRIVE-TRAIN light came on. It comes on while I'm cruising along a smooth road at around 30 MPH. I took one longer trip of about 60 miles and the light did not come on at all.

Brainsy

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Friday, May 29th, 2020 AT 11:56 AM

JACOBANDNICKOLAS

MECHANIC
110,176 POSTS

Hi,

That's interesting. I have to be honest, I'm not sure if a Deep Scan is the same as checking the CAN buss system, but either that needs done or it needs checked when the light is on.

Do you think that is what he referred to when he said Deep Scan?

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Friday, May 29th, 2020 AT 6:17 PM

BRAINSY

MEMBER
6 POSTS

Hi again,

I finally got to my garage with the yellow wrench light on and it showed as P0341 Cam Position Sensor. At least I now know where to look for a problem. My mechanic was surprised that this code was not getting stored in the vehicle computer, but felt that the problem might be occurring in very short intervals, as it only shows up occasionally and clears by pressing the reset button on the dash, or by turning off the ignition switch. And the vehicle performance seems unaffected.
As an aside (I think), I filled up with gas the other day and the vehicle would not start afterward. Lights all worked, dash lights came on, but not even a click under the hood. Believe me, I shook the gearshift around a lot while trying to start, and disconnected/reconnected the battery before I called for a tow. When we got to the garage the mechanic got in and turned the key and it fired right up. I'm thinking a flat spot on the starter. Recently the starter remains engaged for a short time after the engine has fired - gets dragged around, so to speak, and it's taken me 156,000 miles so it seems logical.

Brainsy

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Thursday, June 11th, 2020 AT 5:18 PM

JACOBANDNICKOLAS