[viXit]

Car in question is a Safari Storme 2013.

I have an aftermarket install, Pioneer AVH-X7850BT head unit.

Problem

:

I have a habit of waiting for system checks to complete before cranking the car, so I wait for all the warning lights to turn off (ABS, Airbag, Glow Plug etc.) So the music system turns on and boots up, but when I crank the engine, the power to the head unit is lost until the engine starts again. How can I fix this? I don't want the system to boot up and down constantly.

Part of the problem, although avoidable is the motorized screen. It opens when the system turns on, but when I crank the car, it closes and opens again when engine starts, due to the momentary loss of power. How can I remedy this behavior? I have observed other cars where the music system constantly gets power during the startup process. I understand that this is designed like this, but want to change it.

Any help and info is very appreciated. Thanks in advance.

[vishy76]

This is a failsafe measure built in to ensure all the juice from the battery goes to the starter. The power line to certain unnecessary components is usually cut off during cranking and then restored

One simple way of overcoming such interruptions is integrating a capacitor of suitable specs on the power line of the HU. This will make up for the momentary loss of power to the HU. Adding a diode will ensure the current doesn't flow out of the capacitor into the rest of the circuit.

When you flick the key on, power will come on and the capacitor will store it. The diode will prevent tue current from the capacitor from backtracking. Once the interruption occurs, the capacitor will offer up the current it has stored for long enough to keep the HU alive until the engine has fired up.

Here's a video illustrating the same:

https://m.youtube.com/watch?v=gtd6dAwq3QY

[Mr.Boss]

Originally Posted by vishy76

One simple way of overcoming such interruptions is integrating a capacitor of suitable specs on the power line of the HU.

Wondering what should be the size / spec of the capacitor to power the HU during cranking.

Some more details here
https://classicbroncos.com/forums/ar.../t-244208.html

[Kosfactor]

Originally Posted by viXit

I have a habit of waiting for system checks to complete before cranking the car, so I wait for all the warning lights to turn off (ABS, Airbag, Glow Plug etc.) So the music system turns on and boots up, but when I crank the engine, the power to the head unit is lost until the engine starts again. How can I fix this? I don't want the system to boot up and down constantly.

Your habit is good, not waiting for the car to finish its song and dance may also shorten the life of the battery / starter etc.

If the signal wire for the audio system to turn on is connected to the accessory section of the ignition key and the battery is in near full charge and full working order, the stereo will not turn off while cranking the engine. If your vehicle is doing a lot of short trips wherein the battery is not getting fully charged then this problem is hard to avoid - it being diesel.

[Jeroen]

An easy way to fix this is to find a permanent power supply.

One way of checking this is to measure voltage on each circuit in the fuse box during cranking. On both our Fords, and my W123 the cigarette lighter stays permanently powered, even during cranking. Easy to pick up a positive supply from such a circuit.

Also, cabin light often stay on during cranking. Easy to check, crank with the door open. If the light stays on, you have found a suitable power source.

Good luck.

Jeroen

[abhishek46]

I was just wondering, doesn't your music system have a power off/on button?

Before you shut down your car, try to power off the music system.
When you start your car again, the music system should stay off (unless you press the On button).
This is how it works in my car, but, this behavior could vary, from car to car.

[viXit]

Originally Posted by vishy76

This is a failsafe measure built in to ensure all the juice from the battery goes to the starter. The power line to certain unnecessary components is usually cut off during cranking and then restored

One simple way of overcoming such interruptions is integrating a capacitor of suitable specs on the power line of the HU. This will make up for the momentary loss of power to the HU. Adding a diode will ensure the current doesn't flow out of the capacitor into the rest of the circuit.

Thanks Vishy, I'll make a trip post my exams to the store and get me some capacitors. In the meanwhile, if you complete this mod on your car before me, pls share the specs of your capacitor and diode.

Congratulations on the 5 stars, they look like they belong under your name.

Originally Posted by Kosfactor

Your habit is good, not waiting for the car to finish its song and dance may also shorten the life of the battery / starter etc.

Oh!, This is news to me.
I have to admit, I don't always wait for the song and dance on my push button start cars , it's simpler on a conventional key barrel start.

If the signal wire for the audio system to turn on is connected to the accessory section of the ignition key and the battery is in near full charge and full working order, the stereo will not turn off while cranking the engine. If your vehicle is doing a lot of short trips wherein the battery is not getting fully charged then this problem is hard to avoid - it being diesel.[

I'm afraid my car is not so smart, I recently changed the truck's battery after it died and the behavior was the exact same, even with the new battery.

Originally Posted by Jeroen

An easy way to fix this is to find a permanent power supply.
.
.
.
Also, cabin light often stay on during cranking. Easy to check, crank with the door open. If the light stays on, you have found a suitable power source.

Cannot remember , but will check.
My music system also displays the time. And it doesn't have an internal battery. It relies on the constant 12v to keep it's clock ticking. Since there is a constant 12v supply already, I thought I could use it, but that would mean that my Head Unit would never turn off. I would use that as my source if I can figure out to make it work according to my needs.

Good luck.

Thank you sir.

Originally Posted by abhishek46

I was just wondering, doesn't your music system have a power off/on button?

Before you shut down your car, try to power off the music system.
When you start your car again, the music system should stay off (unless you press the On button).
This is how it works in my car, but, this behavior could vary, from car to car.

It does, but it doesn't need to be manually turned off/on every time.
And even when it's off, it stays connected to my phone via Bluetooth.

Originally Posted by Mr.Boss

Wondering what should be the size / spec of the capacitor to power the HU during cranking.

Some more details here
https://classicbroncos.com/forums/ar.../t-244208.html

Thank you for this useful link sir.



EDIT
adding the screenshot of my wiring diagram for reference.

Also, link to the user manual , snapshot is from page 51

AVHX7850BT-Instruction-Manual.pdf

[Kosfactor]

Originally Posted by viXit

I'm afraid my car is not so smart, I recently changed the truck's battery after it died and the behavior was the exact same, even with the new battery.

Common for most vehicles, The yellow goes to the battery (always powered) - the black is ground (connected always) and the red - this one goes to the ignition switch signal for accessory, gets power only when the key is turned to accessory position or beyond.

[condor]

That's part of the design, like fellow members have pointed out. I am just repeating the points:

I do the same as you do - wait for all lights to go off -ABS is the last, - before I start the engine. My HU is in power off mode till then. But this doesnt work at signals when I switch off the engine - the HU will be active at that time. But then I have a basic unit, and no problems observed thru the years. So I just leave it that way - switch off the HU when I park after my trip. And switch it on after engine starts.

[nagr22]

Dear viXit, I think I can offer a partial solution by referring to a thread that was created by none other than yourself . This will solve your concern of not wanting the music system to boot up and down so many times. But it will make the process of booting up the system a manual effort, which may prove to be inconvenient.

Here's the thread I am referring to: https://www.team-bhp.com/forum/modif...tons-cars.html (Fill in the blanks! Ideas to fill up blank / dummy buttons in cars)

What you can do is, find a dummy switch spot in your car, put a toggle switch in there and connect it in series with the red wire (ignition signal) mentioned by Kosfactor and you should be good to go.

[vredesbyrd]

Thanks for the question and the info. Same used to happen with either RCD510 or RCD330G on the Superb. Doesn't happen with the RCD340G on the Vento.

[svsantosh]

Only solution is to hot wire the HU to the cars battery and setup a toggle switch in line. Do not take power source from the OEM wiring.

Do not forget to switch off the Hu when you step out and lock the car, else the battery may go dead.

[IP_Man]

It is not loss of power. Engine cranking requires heavy current from the battery that dips battery voltage momentarily. As voltage becomes less electronic gadgets like you mentioned resets.

Simple solution is diode (1N4007) and capacitor (4700mfd/16V). Capacitor retains the charge when battery voltage dips and diode prevents capacitor discharging.

I practically did this arrangement in my previous car to stop reset of MP3 player due to cranking and it worked beautifully.

Originally Posted by svsantosh

Only solution is to hot wire the HU to the cars battery and setup a toggle switch in line. Do not take power source from the OEM wiring.

I have a doubt because battery voltage itself decreases during cranking. Anyway I don't recommend direct connection to the battery without appropriate value of fuse in series.

[Fortunerider]

Hi,

I too have a similar setup with Pioneer AVH - Z9190BT in my SUV. I just turn off the system in HU before shutting down the engine.

When starting the car I follow the same procedure as you and HU does not boot at the start but just the screen pops up. This was the advice from the service associate when my HU conked off a few months back. Luckily it was under warranty.

[hi_on_torque]

Hi,

Removing power to HU is a way to reduce drain on battery so that maximum power can be directed towards starting of the engine. The ignition switch of the car turns off the accessory line that wakes up the HU when you take it to crank position. This causes the HU to turn off.

When the battery is in good condition, leaving HU on will still not cause a serious issue. But as battery becomes weak, there could be a situation that the car could have been started if the HU was not on, but the drain of the HU makes it difficult.

But in my own experience, once battery is in such a state, it is only a matter of a very short amount of time before you won't be able to start the car even with HU off. Moreover, the current consumption is high by the power amplifier. Other than that, the HU consumes very small current (under 1A mostly). That is why, in some cars, the HU itself does not power off, but the power amplifier's power is cut during cranking.

All said and done, HU rebooting due to cranking is quite annoying. Especially with today's scenarios where sometimes you are using navigation, or playing songs from phone using bluetooth etc, the process of getting back to where you were can take a long time.

So, I would want my HU not to reboot. But if I make such modifications, what I would do to reduce the drain on the battery when cranking is to make sure that the volume is turned down, so that the power amplifier is not pulling a lot of current. Especially if you have a sub-woofer fitted. Sub-woofer consumes a very high amount of current when producing powerful base sounds.

Following solutions are possible (and many of you have suggested most of these) with their side-effects:
1. Separate out the wake-up line of the HU and fix a switch. Manually turn on and turn off the unit as you desire. The downside is that you have to do it manually. Also, if you forget to turn it off, the HU will drain battery.
2. A direct capacitor with a diode. This keeps the HU awake for a few seconds (duration of the cranking). This was the first solution I had tried. But I had to use a large capacitor (470uF or larger). The size of the capacitor will depend on how much current your HU consumes from that wake-up line. After some time, the diode got spoilt due to repeated in-rush current of charging the large capacitor.
3. Then I devised a simple delay circuit. I am attaching the diagram. In this, the capacitor is small (100uF). So, the diode did not get spoilt till I sold the car about three years after implementing this. To enhance it further, a small value resistor (~4.7 ohm) could also be added between the diode charging the capacitor and the capacitor.

Hope this helps.