[Black Rein]

Strange electrical and sensor issues.

Hi everyone, I have a 2001 v6 conv. mustang with 150k mi. I'm not sure if these issues are connected but here goes. The issues started with my left turn signal blinking quickly like the light had gone out, yet all lights are fine. This has been going on for months. Next my passenger side window stopped working for a month or so, then works fine for a week then stopped again, this cycled about 2-3 times. I checked all my fuses in the engine bay and under the dash and found one broken that when replaced breaks again. It is a 20A fuse in position 8 under the dash for "engine controls".

This brings me to the most recent issue. My check engine light has come on with several codes:
p1409 EGR vacuum regulator circuit fault
p1451 EVAP system canister vent solenoid circuit malfunction
p0443 EVAP purge/vent solenoid circuit condition
p0161, p0155, p0141, p0135 heater condition (heated oxygen sensor)

I checked all vacuum lines and did find and replace a line with a hole in it to the EVAP canister. I have not checked the codes again so the EVAP codes may be gone. As far as the O2 sensors, all 4 read 0V. I just don't think its possible that all 4 went out at the same time?

I checked my O2 wires the best I could and did not see any issues.

Thanks in advance!

Chris


PS This is not the car in my sig.

 

[wmburns]

FWIIW, the blown F2.8 fuse is the source of all of the DTC codes. All of the sub-systems listed are on circuit F2.8. So that does explain why all of the mentioned sensors have 0 volts.

So now the challenge is to find the fault. Start first with a visual inspection of the wiring harness. Next disconnect all of the affected sensors. Re-connect one at a time until the fuse blows. This will give you a place to start.

FWIIW2, the usual source of this problem is the O2 pig tails contacting hot exhaust after an exhaust upgrade.

 

[Black Rein]

Thanks wmburns!



I have had exhaust work done recently but after I started having the problem. I just came in from rechecking the O2 wires and they look fine as far as I can see and feel.
I will try to narrow down which sensor wires are causing the problem...looks like I need to go buy a few more fuses .

Does this also explain the turn signal and passenger side window?

 

[wmburns]

Turn signal is likely the multi-function switch. It can be rebuilt or get another one from the salvage yard. I have answered this question several times recently.

The window problem can be explained once you realize there is an automatic reset circuit breaker in the engine bay fuse panel as well as the window motor itself. So this offers an explaination why the problem comes and goes.

Find out why the motor is drawing too much power. The usual reason is bad bearings or water in the works.

 

[Black Rein]

Resolution

Well I narrowed the problem down to the driver's side O2 sensor and whatever wiring is connected to it. So I hoped it was the sensor itself, though it had no visible damage and the resistance checked out (didn't check at operating temperature though). So I purchased new sensors and changed them out. Its been a week and no check engine light.

My gas mileage is a bit better but still not where it should be. The other day a CEL P1518 (IMRC stuck open) came on for a couple days then went off. The car still hesitates so something else may still be going on. I will make sure to run some Seafoam through it to help with thte IMRCs.