Delayed Wipers + Turn Signal Flash = Wiper Stop 🤔 (RESOLVED)

[Intuit]

So this is a weird one. Delayed wipers stop working with each turn signal flash. When turn signal lights turn on, the delayed wiper makes a dead-stop mid-sweep. When the turn signal lights turn off, the wiper may resume movement. Doesn't matter whether it's the left turn sig, right turn sig, or hazard lights. At least temporarily, the wiper may need to relearn it's park location at the base of the windshield. Continuous wiper on normal or fast is not affected.

I'm suspecting a ground issue.
I do have resistors on all four corners for the LED turn signals.
Hopefully it's not an issue with the BCM.
I'll post more as I investigate and discover.

I understand that we can pull codes from the BCM using ForSCAN ? May look into that.
One of my troubleshooting steps will be to individually disconnect the mirror and corner resistors and lights to see whether the malfunction behavior might be affected.

 

[Intuit]

Some other details.

The rear wiper is unaffected. Doesn't matter whether it's told to sweep or is set on its normal delay mode.

A simple workaround for this (at least during the day) is to turn the headlights off.
The malfunction behavior ceases entirely if the headlights fog lights are deactivated.

Malfunction behavior does not occur with parking lights.
The Euro model headlights do not have the yellow corner parking lights of the OEM.
Doesn't matter whether the fog lights are on or off.
Will later confirm that the malfunction persists with high-beam activation.


Haven't taken any troubleshooting steps yet as this is low priority.
Looking more and more like a ground issue; either with the main ground between vehicle and battery, or ground with the BCM.
I'm all LED except high-beams and license plate light. Headlights are among the biggest consumers of power.

 

[Intuit]

Gradually moving to new computer, just got the Service Manual program up and running again.

Wipers...


Turn sigs...

 

[Intuit]

Yeesh. G201 ground will be fun to get to if I want to check that.
Due to prior humidity levels I've seen rust behind the dash. But that ground is shared by everything and the only other module that has required a power reset via fuse-pull since 2016 (3 times so far) is the Blower Motor Control module... which also happens to be high load.

BCM appears to be located below the glove box and operates on ??? fuse.
Multiple fuses feed individual circuits within the BCM so if I cannot find one for the BCM itself, may just disconnect the battery as a reset.

Before I check that ground,
* Use FORScan to check BCM for codes and run BCM diagnostic
Will follow the general rule and look at the things I've messed with first.
* Disconnect DRL
* Disconnect Turn sig resistors
* Turn off subwoofer amplifier

 

[Intuit]

Update:

Delayed / Intermittent wipers and wiper parking in general has gotten progressively worse.

Seems to improve a little if I place more miles on the car. (normally sits a lot)

I can see the volt meter quickly/briefly drop as the wipers activate.

Pretty sure the car battery is the chief component to this issue.

If I don't update this thread, assume that the issue disappeared with a new car battery.

 

[Mycooking]

These cars seem very sensitive when the battery starts to show its age or the alternator is on its way out struggling to keep the car powered and the battery charged. Cheapest thing is the battery first like you said you already plan to replace first.

 

[Intuit]

EDIT 23y06m19d

Multiple Choice Question...

You have a problem with the intermittent wipers stopping with each turn signal flash. BCM code is "Front Wiper Park Position Switch: Signal Stuck High". Is it the...
A) LED Turn Signal Mods
B) Wiper Park Switch (inside the motor)
C) BCM
D) Wiring harness fault
E) Wiper Stalk Switch or Steering Wheel Clock Spring
F) Bad LED Headlights

Copy & paste the text below, or zoom in for the explanation.

If you guessed the letter f, you win! You'll receive a brand new noogie by mail come February 31st. The LED headlights have a built-in circuit that prevents computers from warning about a burned out headlamp. Like adding load resistors to the turn sig circuit, it generates current. The circuit in both lamps had gone bad; was dumping excess power in rapid pulses, off to ground; messing with BCM function.

/EDIT 23y06m19d

===============================================================================================================================



Intermittent problem came back not long after updating this... then it disappeared for awhile... then back... and so-on. So I decided to lay this matter aside either until it got more consistent or/and more annoying. 😂

Anyway, I've narrowed it down to this only occurring when my LED headlight is connected on the passenger side. If I disconnect only that headlight, the park signal quits getting stuck high (at 14v output from BCM). Swapping LEDs between sides have no impact.

I'll pickup a standard H7 halogen from the store tomorrow. I'll also be voltage drop testing ground between the headlight harness low-beam and select BCM pins. I'll also voltage drop test select BCM pins to verify that it's getting the power it should. Electronics can exhibit odd/unexpected behaviors with insufficient power. But at this point and with a bunch of other completed checks and tests I haven't mentioned, it looks like I may be needing a BCM. Visually inspected the BCM and the only thing I noticed was that none of the pins were soldered; only crimped in. So I soldered them all, which made no difference. Neither did throwing a part at it (wiper motor) make a difference. While the problem is annoying, fortunately I'm not really frustrated by the investigation process. It's interesting learn more about how this vehicle is setup.

 

[Intuit]

I've been watching the volt meter instead of relying on the wiper physically parking because the wiper may still manage to park (intermittently) even though the BCM appears to maintain output to that park switch. The volt meter is a much more reliable indicator for the presence of the issue.

Well... installed a standard halogen in the passenger slot and... intermittent wiper issue disappears. Reinstall either one of the two LED headlight to that passenger side and the problem immediately resumes. Weird because they've been installed since 2019.

https://www.amazon.com/gp/product/B07RSFP4YF/

These LEDs have been great. Looking over the listing, I noticed two things.

One, they're 70 Watt and two, they supposedly have a built-in canbus adapter so as to not trigger outage warnings. (our cars of course don't care if a headlight is out)

The 70W may mean 35W a piece... don't know. I think standard halogens are 55W a piece.

Tried looking in on how the Canbus works and one says they merely watch the current and generate a trouble code if the current draw is too low. So the headlights may simply have incorporated load resistor(s)? If so, do the failure modes for load resistors include shorting? (something that may dump load off to ground)

I could try grounding low-beam/DRL back to the chassis along with the turn-sig resistors or replace the LEDs. Stay tuned...

 

[Intuit]

Installed different LED headlamps and problem ceases.

In addition, the driver side DRL quit flickering. Looking at the pin-out (post above) for the headlamp, the low beam headlight and DRL share the ground on that pin.

So that was it! The prior LEDs were dumping off a bunch of noise to ground. The TLE7240SL Datasheet (PDF) - Infineon Technologies AG IC probably uses ground as a reference to perform its functions.






Back-probed using a straight-pin, the eight pin on the smaller blue plug, top-right, for park switch reading.

 

[ogminlo]

I think I'm seeing something similar manifest as a turn signal fault on the driver's side. Intermittently, I'll get a rapid signal indicator in the cabin (like you'd see in a resistance-regulated signal setup), and no illumination of the front turn signal bulb. This condition comes and goes. I thought it might be a failing battery or alternator, but a simple multimeter volt check showed them in normal range, at least. I suspect a similar grounding issue that is either a fault in my euro projector adapter harness (likely) or possibly a similar issue with the bulbs. It briefly happened on the passenger side once or twice, but has been much more common though not consistent on the driver's side.

 

[Intuit]

I must be misunderstanding or missing something. From what I think you've described it sounds like the circuit is behaving as intended. The turn sig LED may have a bad solder joint and/or developed an intermittent short of some kind. If you have separate turn sign resistors, the indicator flash rate should not be affected even when the turn sig LED is completely removed from the circuit.

Side note, I did replace my higher wattage load resistors with lower wattage... the idea being, less unnecessary load dumped onto ground and less unnecessary draw from the BCM.

 

[ogminlo]

I must be misunderstanding or missing something. From what I think you've described it sounds like the circuit is behaving as intended. The turn sig LED may have a bad solder joint and/or developed an intermittent short of some kind. If you have separate turn sign resistors, the indicator flash rate should not be affected even when the turn sig LED is completely removed from the circuit.

I don’t have LED turn signals at all, every turn signal bulb on the car is incandescent still. But intermittently, the front driver’s side will just not fire and the rest of the system goes double time. It has happened briefly on the passenger side a couple times, but I’ve even seen it start rapid and during blinking slow down to normal. It has to be a loose pin or worn ground wire to act like that, right?

 

[Intuit]

rest of the system goes double time

Question: If you pull one bulb, does it affect the blink rate for both sides?

The answer potentially broadens the scale of investigation.
If the answer is yes, remove, inspect the socket and filament-bulb and re-seat each one.
If the answer is no, and only one side is affected, then agree that it likely points to some systemic issue though, it's possible to have more than one defective socket/filament-bulb.

Also as a matter of curiosity, does it affect the hazard light blink rate?

 

[ogminlo]

Question: If you pull one bulb, does it affect the blink rate for both sides?

The answer potentially broadens the scale of investigation.
If the answer is yes, remove, inspect the socket and filament-bulb and re-seat each one.
If the answer is no, and only one side is affected, then agree that it likely points to some systemic issue though, it's possible to have more than one defective socket/filament-bulb.

Also as a matter of curiosity, does it affect the hazard light blink rate?

It does not affect hazards. I noticed it happening and tried the hazards as a sanity check, and they worked normally. It isn’t even consistent enough for me to try to trace it, it just comes and goes, no apparent link to temperature or other environmental factor. I’ve had it work fine in last week’s heat and in the earlier cold. Then again it also didn’t work in those same temps. Initially I thought it was an indicator of a failing battery or alternator, but those checked out ok on my multimeter, at least.

I’m going to stay by building a better-quality adapter harness and see if it continues. I just need a free evening which have been in short supply lately for me.

 

[ogminlo]

It’s the adapter harnesses I built. Just snugging them up completely resolved the problem, so I will definitely be building better ones out of better materials with lessons learned to keep the gremlins at bay for good.