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Service RSC Now + Code P0117

bluesq

Member
Joined
April 17, 2019
Messages
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Year, Model & Trim Level
2008 Explorer Limited 4x4
I just started getting a Service RSC Now message with beeping that comes up ever 5 minutes or so. The traction control light is also illuminated as is the check engine light.

I pulled the codes. I expected to see something about a wheel speed sensor. The weird thing is, the code I pulled was P0117 which corresponds with the coolant temp circuit. This makes sense because I am seeing the temp gauge bounce around (will appear cold [below "C"] then up to normal operating temp).

What I don't understand is why the traction control light turns back off when the temperature is reading correctly. It goes back and forth like this in a cycle - the temp goes to below "C", the traction control light turns on, the "Service RSC Now" message will appear and the alarm starts. The temp goes back to normal operating levels, the traction control light turns off. The "Service RSC Now" message will not come back on until the temp reads below C and the traction control light turns back on.

The ABS light is NOT on. When I am at a stop and the temp gauge is below C, the engine fan spins like crazy, probably because by default it has no idea what the temp actually is. I have not noticed any weird braking issues or limp mode or anything like that.

The following has been replaced within the last year:

Front wheel hubs
Thermostat and housing with temp sensor
PCM

I'm confused, what does the RSC have to do with the coolant temp sensor? The issue seems to be related based on the lights and gauges. May be just another bad PCM?
 



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Possibly one of the abs sensor wires short cut to temp sensor wires...
 






Actually happened today, pretty much goes back and forth like this. Temp gauge goes to C, RSC goes ballistic along with the engine fan. Then temp goes to normal and everything is fine. Then back again.

Someonepleasestopthisalarm.jpg


Thankgodtheringingstopped.jpg
 






check your various ills and see if they use the same fuse/relay. I had some illogical symptoms and it turned out to be a fuse that was not super tight in the connectors. It would only happen on bumpy roads. I found the fuse that had the unrelated symptoms going through it, started the engine, gave it a wiggle and engine died.
 






check your various ills and see if they use the same fuse/relay. I had some illogical symptoms and it turned out to be a fuse that was not super tight in the connectors. It would only happen on bumpy roads. I found the fuse that had the unrelated symptoms going through it, started the engine, gave it a wiggle and engine died.
Interesting but I am not seeing that the coolant temp sensor nor the RSC has a fuse. I think that's all directed through the PCM. :dunno:

I ordered up a Motorcraft brand coolant temp sensor. For $22 I'm going to start there and see if that does the trick. A couple months ago I replaced the thermostat housing with an aluminum Dorman brand one because the original plastic one cracked. That came with it's own aftermarket coolant temp sensor already installed so maybe it's faulty. Will know shortly.
 






RSC might be rolled into an ABS fuse. I looked at my wiring book and did not see a fuse or a ground with ABS and ECT together or close. Same for pin in the PCM connector which I attached. ECT is pin 18 (V6 engine)in the C175E connector which is the bottom one looking at the PCM.
Coincidently it's fuse is F42, the one that caused me problems!
Good luck with your new part!

C175E PCM Connector.jpg


Po117.jpg
 






Of course...the engine coolant sensor is a screw in type on this metal aftermarket thermostat housing and not the clip in so the one I ordered will not work. Anyone know the OEM Part # on this? Or should I just ditch this thing entirely and go OEM for the housing too?

20240206_165218.jpg
 






RSC might be rolled into an ABS fuse. I looked at my wiring book and did not see a fuse or a ground with ABS and ECT together or close. Same for pin in the PCM connector which I attached. ECT is pin 18 (V6 engine)in the C175E connector which is the bottom one looking at the PCM.
Coincidently it's fuse is F42, the one that caused me problems!
Good luck with your new part!
Thank you for that info. I will check those for sure. I have some spares, might just replace them anyway.

One thing I noticed, the temperature reads fine with ignition is in ACC On. When I turn on the ignition is when the temp reading fails.
 






Update: I contacted Dorman about the coolant temperature sensor attached to their metal thermostat housing. They actually responded very quickly. Part number is TX87. I got a Standard Motor Products TX87 and swapped it out. Problem solved. $3.50 fix.

Not sure why a faulty coolant temp sensor would make the RSC freak out but that's what it is. Should note again, the ABS light did not come on. Just the RSC warning and the traction control light, as well as the check engine light with code P0117 (low voltage on the engine temp circuit).
 






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