Power Delay for Diesel Vehicles

[samweston]

Greetings all,

 

I built this unit from surplus parts to solve the problem of interrupting the booting sequence each time I start my diesel Ford Excursion. When you first turn the key in a diesel to heat the glow plugs, power is switched on to the audio/nav unit and it starts to boot, then in a few seconds you turn the key to start and it cuts power to the audio/nav interrupting the boot and it has to start over again when the key is released.

 

I don't have any hard numbers but several installers that have had problems with pioneer audio/nav units recall many being in diesel vehicles so my theory was, "damage due to interrupted boot sequence". At first I put in a toggle switch to manually control the power to the Pioneer but that got old real quick.

 

This unit takes the place of the toggle switch I was using. I adjusted the delay time to 8 seconds and haven't had a "double boot" yet. You can adjust it to your vehicles needs. I found the relay in an electronics surplus store for $7.00. The relay's coil is wired to the existing +12V switched power source and ground, then use the N/O (normally open) contacts to switch the power.

 

Hope it helps extend the life of your unit as I "believe" it is for me.....

 

Sam

[Kristifer]

Awesome, I'm going to give a try. THANKS!

[ablackformula]

Instead of installing the delay timer, you could've also rewired the stereo:

 

find a wire that has +12V during crank and run (and acc also I guess), and use that as the ign wire to the radio. This way, w/ the key in run, the unit will start to boot, and will not lose power when you begin to crank the engine.

[samweston]

Thanks for the reply ablackformula,

 

That was my original solution but after testing dozens of wires under the dash (including the factory radio power supply) I still couldn't find one that was switched by key and stayed on when the key is turned to the start position. I tried them all including power ports, window circuits, a/c fan and various other circuits. They were either on full time or switch off momentarily when the key is moved to the start position.

 

If you find one, please post it....

[ablackformula]

That depends on your particular vehicle, where a factory wiring diagram is needed..

 

There's probably a wire right at the ignition switch (or base of the steering column) that has the wire since the ignition switch is the source of it. Other than that, the fuel pump would get 12v all the time, as other various engine components. But you'd probably want to use a relay so you don't sacrifice power to the fuel pump if the stereo went a-wire, in which case you'd have to install other hardware as you already have. Perhaps it's a wash and the way you have it now is just as well?

 

But, now that I think of it... here's a question about general car audio:

 

If the radio itself has a wire that's hot all the time, and a 12v ignition source.. when the radio is on and using power, is it taking it from the hot source and just using the ignition as a low-current turn-on signal? If so, maybe you'd be able to use the fuel pump control with no worries.. I'm babbling now..

[skicrave]

Many vehicles do not have a switched 12v connection that isn't interrupted during cranking. This depends on a number of factors, from the design of the vehicles electrical system to the capacity and quality of the battery.

 

The switched 12v is just a trigger to turn the system on, so it doesn't require much current.

[ablackformula]

I understand that most vehicles do not have an uninterrupted run/crank 12v signal for accessories, but my idea was to grab it at the ignition switch harness, where that wire would certainly be present. Other than the question of the radio taking it's main-power current from the ignition-switched wire (which you're saying it doesn't,) there should be no problem tapping into this line to run to the radio (which luckily, the radio and ignition switch harness aren't too far away from each either to run a jumper wire.) With the delay timer samweston already installed, he's already gotten the job done, I was just stating that using this method wouldn't require extra parts.