Unique flashing CEL debacle

Unique issue-CEL flashes and truck stalls with right turn signal AND blower on. Left turn signal, good. Left turn signal and blower on, good. Right turn signal, good. Right turn signal AND blower on at the same time= flashing CEL and engine stall. Engine returns to normal after turning off blower or turn signal. 98 3.4l 4x4. Any ideas? Associated fuses, relays and grounds seem to be good.
Thanks

 

You need to do a code pull and see what DTCs are stored, but off-hand my first guess would be the turn signal relay. What kind of stall is it? Sudden/instant, or prolonged/sputtering?

 

I've tried pulling codes, nothing shows up on scanner. It's a prolonged, sputtering, shuddering stall the goes away immediately (along with flashing CEL) when I turn off either the turn signal or the blower.

 

Sounds like you got a short somewhere. Maybe a bad ground.

That should be fun to trace.

 

So blower motor being energized causes a misfire?

 

I agree with this... you've got electrical gremlins

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Blower motor in conjunction with right turn signal only causes engine stall.

 

without taking pictures of the wiring diagram and uploading them to validate my thoughts the ONLY thing these things have in common is the ground point IE which is located the right of the glove box on the inside of the support member. It has White-black wires, how many, the manual does not state.

 

Flashing CEL means you have a misfire and unburned fuel is going into the exhaust which can overheat and damage the catalytic converter. The flashing is a strong suggestion to stop and turn the engine off as soon as possible and figure out why you have a misfire.

Since it only happens with the electrical load it suggests it's not a mechanic problem with the engine. It sounds more like with the electrical load reduces the power to the coils so you get a weak spark and stall out.

First thing, I would check your battery voltage with engine running. You could have a weak alternator output and the extra load is causing the voltage to drop. Then turn on the blower and check voltage.

You said grounds are good. Did you check the ground for the ECU? I'm not sure where it is on the 3.4L. Also check for clean and tight battery terminals.

 

I've yet to check the ECU ground, Ill have a look.

Batt terminals are clean and tight.

Voltage with engine running was 13.8, voltage w/ blower running was 13.7

Thanks for the input!

 

If grounding is suspected here the common for possible grounding issue: blower relay and front turn signal use the same ground as EFI relay. Bad grounding would make EFI relay to cycle and then the engine is affected.




Ground point EA is on Front Left Fender,



Junction connector J9(A) J10(B) is near by:



Just some things to check

 

According to that diagram, so does the LH front signal

 

LH front signal uses different connection in junction and different ground wire (same ground point tho).

 

You guys are rad. Thank you. It was the EA ground. Two wires share the same ground, one had severed. Crimped a section to the broken one to extend it and grounded it a different bolt in the engine compartment. Problem solved!

 

In case the possible solution RysiuM gave (1st choice) doesn't resolve it, there is also a common grnd point between the blower resistor and the combi meter("IE"). It is near listed as right end of the reinforce, meaning the bar that hold the instrument panel (dash) in place.

 

Agreed - in my experience most ground issues relate to the physical ground point. Glad the OP got it solved... please, don't hesitate to call me whenever I can be of no help at all again!

 

excellent, excellent. I didn't have time to do all of the leg work when I replied.