Thread: Minor issues, major annoyance. Help appreciated.

Hey everyone, I'm new to the Grand Prix world, I've had my 08 "Base" Model for a little over a month now, and I'm in love with the thing. Since i bought it, it's had hyperflash in the signals and a few other minor issues that I've flushed out, but I'm still getting hyperflash. When I bought the car it had more lights blown than working, so I replaced everything but the headlights with LED bulbs. Yes, I'm on of "those" guys and the LED headlights are in the mail. I know that you typically need to replaced the signal flasher to kill hyperflash, but this car apparently doesn't have one, and it's supposedly part of the multifunction switch. I've also been having an issue with the right turn signal activating my high beams, so I have one of those on the way, hoping it will end the hyperflash issue. If that doesn't work, I can live with the hyperflash until I have the ambition to wire in load resistors.

My other, far more aggravting issue, is my new touch screen stereo. I bought a Pioneer AVH-110BT 6.2in touch screen head unit, everything is installed very cleanly, and I bought the PAC RP5-GM11 Wiring Harness to retain the factory stereo controls, etc. To my knowledge, I've wired everything correctly. I've tried every setting on the control box, but can't get the stereo controls to work, and I've lost my Sirius XM altogether. I don't know if the loss of XM is because the stereo may not be compatible, but the wiring harness is supposed to retain that, I believe through the AUX input provided on the rear of the stereo as there are connectors for everything that the factory stereo has wires for. I know there are typically two remote wires on a stereo harness, one blue for the aftermarket sub amp, if applicable, and one blue and white for the the factory remote system. I may have the colors swapped in my head, but I matched all the colors as the directions said to, but I'm retaining none of the stereo controls and I would really like to have that option as it's far more convenient than leaning forward or picking up my phone to switch songs.

The other issue I'm having since the stereo install is my HUD calendar keeps resetting, and I'm unsure if this has anything to do with a misplaced wire, as well as my parking brake light won't shut off. There is a wire on the harness for that, but I wasn't sure if it was necessary so i didn't connect it yet. The parking brake on the new caliper doesn't like to release, and I'm thinking that could be a bad cable, so I've ordered a new one for each side that I'll be picking up tomorrow, hoping that's the issue.

Another issue I'm running into with this car is a low brake fluid light that just will not go away since I had to replace a caliper. My brake fluid is topped off, bled, et all.
I'm thinking the sensor could have gone bad as this car was in kind of rough shape when I picked it up, but I also don't know if this is related to the parking brake issue.

And...finally, the dreaded Vent Valve Solenoid Intermittent CEL light that just WILL. Not. Die. I've replaced the vent valve solenoid and PVC hose that goes with it, as well as added in the wiring harness adapter, and the light will not turn off with my Global OBD tool, if I switch modes to the OEM enhanced I can turn the light off, but it immediately comes back with the exact same code. Am I missing something?

Originally Posted by tzerilli

if you have led blinkers I believe the only way to get rid of hyper flash is to install resistors or buy bulbs with resistors in them also I just straight up cut my parking brake cable since it was sticking and I don't get the parking brake light only time I get the light is if I accidentally press in the parking brake pedal. which then I just press it in again to undo it. either its still press in and you need to press it in further to unlock it (kinda like a seatbelt on some cars) or there is a sensor that detects that the pedal is in that has gone bad I assume its right by it

I was thinking it might be the switch, and since it was only $4 I ordered it along with some other parts.

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Originally Posted by wowitsfast

LM470 LED Turn Signal Flasher - Flashers, Resistors - Extras | Diode Dynamics

This is how I fixed my hyperflash. Took 3 mins and gives you a nice new blinker sound lol. Idk if this one is right for your car so check it out if you decide this path

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I sell these from another brand at work, actually, and that solved my hyper flash in my old Jeep, but the problem is the 08 Grand Prix doesn't have a flasher relay, it's built into the multifunction switch, which I'll be replacing soon to hopefully solve this and another issue.

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Originally Posted by wowitsfast

So you can buy a multifunction switch with a LED turn signal flasher built into it?

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Not to my knowledge, but from what I've seen with some newer cars, the multifunction switch with the flasher built in or localized to the hazard flash is usually compatible with LEDs. Mine is actually malfunctioning in another way as well, so I'm hoping this solves the issue.


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Just wait till the dash starts shutting off randomly or you get a million DIC errors. You'll really love that PAC then, lol

They don't all fail, cause weird data issues and die horribly. Just most of them.

Don't take my word for it, though. If you're on the fb groups, search "dash lights off" and there's dozens of posts with aftermarket stereos and similar problems.

The parking breaks stick sometimes. Doubt that would cause a leak. Throw on a new level sensor, give it a whirl. They're like $12 bucks local.

Originally Posted by SaukRapids

Just wait till the dash starts shutting off randomly or you get a million DIC errors. You'll really love that PAC then, lol

They don't all fail, cause weird data issues and die horribly. Just most of them.

Don't take my word for it, though. If you're on the fb groups, search "dash lights off" and there's dozens of posts with aftermarket stereos and similar problems.

The parking breaks stick sometimes. Doubt that would cause a leak. Throw on a new level sensor, give it a whirl. They're like $12 bucks local.

I actually just changed the level sensor today, nothing changed. Next project is parking brake cables and sensor, as those are the only other parts that were moved/touched during the process immediately before the low level light came on.

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This is all great info, guys. Thank you all! But my biggest issue/concern is the CEL that won't go away for the vent valve solenoid. I've been debating starting a thread for that but I don't know if it's already been answered or would even be worth the effort.

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