How to avoid Reboot when starting vehicle

[Alexei Navalny]

I used a 12v relay from Radio Shack. Must be electronic type, not automotive type. I took 12V (from the yellow wire actually) to the relay (you need to solder or have someone do it for you). The other side of the switch (relay) goes to the red wire. I then took a line from the accessory (was already there to the AVIC) to a 1Amp diode (neg side). On the pos side of the diode I connected a 4700uf capacitor (also from RS)and soldered this to the coil of the relay. The other coil wire went to ground.

 

There is, in my case, a 3 second delay of the unit shutting down. Restarting does not cause a reboot, and even after turning off the key and opening the door, I'm sometimes shutting the door before the unit shuts down (disconcerting to service men, I have to tell them it's ok). Works for me.

hg

 

 

Excellent, sounds like just the solution I was looking for. Can you give a detailed parts list (RS part #s would be great!). It sounds like a fairly simple circuit, but a diagram would be great. I'm sure many people here would appreciate it.

[Harvey_Gordon]

I don't know how to add diagrams here, but I'll explain as well as I can.

 

I used a RS relay - part number 275-0249. I soldered (in the house) 4 connections to it. Across the contacts (the switch) I soldered a wire to each side. I used a RS diode - part number 276-1103 (or you can use an 1104 if you have one on hand as I did), and soldered the + (banded side) to a RS part number 272-1022 capacitor's + side, then soldered this to one side of the coil (it doesn't matter which side either). I also soldered a short piece of wire to the neg side of the diode as well.

 

Now--- I soldered a piece of wire, about 4" length (you'll figure the length yourself in your setup) to the other side of the coil and ran it along side of the capacitor and hooked the neg of the capacitor to this. I then (actually at the same time) added an additional length of wire to this negative connection. I checked all connections, then wrapped everything in black electrical tape so I had a small black package with 4 (marked) wires coming from it. Be sure to mark which wire is which. Use masking tape or I used the end of a trailer wiring kit which had 4 different colored wires. Write down which is which. Don't rely upon memory.

 

Now out in the vehicle, using wire crimps, I connected the capacitor negative to a good ground. I cut (broke apart actually) the connection going to the red wire of the AVIC. To the wire COMING FROM THE VEHICLE, I connected the wire going to the diode. To one side of the switch (again, doesn't matter) I hooked the red wire going to the AVIC. The last connection is to any 12V source that's always on. The Yellow wire going into the AVIC can be spliced into. Do NOT separate the connection, just splice into it. Actually, I ran a new heavier fused wire directly from the battery to the yellow line, then tapped into it. This stopped my AVIC from rebooting for no reason.

 

That's it. Hope it helps. Good luck to you.

 

hg

[Alexei Navalny]

Harvey, I am not a complete novice at circuitry, but I'm trying to draw a schematic of this and my head is starting to hurt. It seemed so simple in your inital post, but now I'm confused. Mainly, the relay you used is DPDT, which has 6 contacts (not counting the 2 for the coil). I downloaded the spec sheet for it.

 

What I came up with relys on two assumptions I'd like you to verify:

1. You only use one side of the DPDT (a DPDT is essentially two SPDTs) - so could I use a SPDT?

 

2. Assuming you only needed a SPDT, which contact contacts are used? I'm guessing Common (out to the HU RED) and the Normally Open side (coming from the diode/cap).

 

If you really needed a DPDT, I'm lost. Sorry for the dumb questions, I'm pretty rusty and not exactly solid on the terminology. BTW, I understand what you are doing with the diode/cap and think I understand the polarity issues. Once I've got this 100%, I'll try posting a schematic.

 

RonS

 

 

[Harvey_Gordon]

Sorry. I've been away. I work week-ends.

 

You are correct. You can use a SPST switch (relay). Even though this relay has a high enough rating, it's also cheap enough to use, and I double contact it. Any idea what I mean? I use both sides of the SP switch. I solder them in paralell (now that can't be spelt right - oh well). I use both of the DP connections. Is this needed? No. Then why? It's just my security/backup in case of a contact malfunction (if the coil fails, it needs replaced). Once the dash is all back together, I don't want to have to return to it unneccessarily. So, ... sorry for confusing you, but you only need the relay to act as a switch (replaces the key).

 

hg

[Alexei Navalny]

Well, I collected an assortment of parts I found lying around home and office (not the same part # as you used. Basically 12V SPST digital relay, a cap, and a diode. Started soldering and quiclky realized I wasn't going to make a nice neat bundle out of this. Then, I accidently broke off one of the solder leads on the relay (coil), and gave up.

 

Then I thought, there must be some off-the-shelf solution - this application isn't that unique!

 

So I googled "relay delay", and found the PAC TR-7. (through Amazon $19.49 linky) It does many things, and is primarily used as a parking-brake bypass for Alpine NAV units. But is also is a relay with a programmable delay for both ON and OFF (up to 4 min:15sec). The manual makes it look a little daunting to program, but many have said it isn't that complicated Manual. See feature #12. Only 4 wires are needed for this function (ground - black, +12 V - red, ACC - green, 12v out - blue).

 

Installation of the unit is very similar to your design. So for those who:

• would have to buy the parts anyway (probably $ 12 - 15 @Radio Shack or more if you buy a plastic case).
• don't have the skills or tools to fabricate it.
• want to have more control over the OFF delay

then this is a nice clean solution. I just ordered one for myself. I figure my time is worth a few extra bucks.

 

Harvey, thanks for leading the way and designing a nice solution to the rebooting issue. You proved it could be done.

 

Late addition: I discovered that the ACC cut-off (while starting) wasn't my only issue. Seems that the factory radio harness +12V that I am using to power the AVIC also drops voltage or cuts out while cranking the starter. I will need to run a direct +12v circuit from the battery to eliminate this drop. That means I'll have to pull the HU. Project just got to be a big pain-in-the-rump!!! Which means I'll wait until I decide whether to add BU camera & BU wire. I'll just live with reboots till then.

[Harvey_Gordon]

Glad you found a solution. And thanks for finding a $20 relay to do the trick. I had found one, but it was a commercial unit for fire trucks, etc, and it was in the $80 range, so I went to my solution. (...and actually I added a second capacitor to get a 6 sec delay, but that's another story).

Hope it all works out for you. Glad to have (I hope) helped.

 

hg

[castellscl]

I'm gonna try this same thing, but am lost without pictures.

Any help?

[Alexei Navalny]

I'm gonna try this same thing, but am lost without pictures.

Any help?

 

First, a disclaimer: I never got this to work on my car. It seems that the voltage drop while cranking is too much to keep the HU from rebooting. I think this may be solvable, but I didn't feel like it was worth the effort. Maybe an oversized battery will help. That will have to wait a while since mine is only 18 months old. Another possibility is that my factory radio's constant +12v wire really isn't constant. To test that, I'd have to remove the HU and run a fuse protected wire directly from the battery. Again, not worth the effort at this time. So, the solution here is somewhat vehicle dependent.

 

I'm not sure what level of explanation you are looking for. If you have some background in electronics (even introductory); understand what a diode, capacitor, and relay does, then you should be able to draw a diagram with the info here. You need to deal with polarity issues with the diode and cap. You also need an understanding of how the HU is installed (especially the two power feeds). The HU requires constant +12V (yellow wire) and a switched +12v ACC (red wire) which turns ON/OFF the unit with your ignition switch. The problem we want to solve is that most ignition switches drop the ACC +12v momentarily when the key goes from ACC (or ON) to Start. So this causes the HU to reboot. The solution is to not actually feed the ACC wire to the HU, but to run the red wire to a relay - and through the stored energy in the cap, bridge the short voltage drop (over the red HU wire) for a few seconds until the ignition switch returns to the On position. For this to work, however, the constant +12v (yellow wire) needs to maintain at least 10.8v (minimum operating voltage) while the starter is cranking.

 

Since the original wiring for your installed HU may differ, I'll ignore exactly where the red & yellow wires are connected/fused. Just know that the HU red wire is switched, yellow is constant.

 

What you want is to cut the red wire and run it through: a diode, then a capacitor (which acts like a storage battery), then one coil terminal of the relay. The other coil terminal goes to ground (-). So now we have a short delay before the relay turns off the "switched" circuit. On the "switched" side of the relay, connect one lead to the other end of the red wire to the HU. The other "switched" terminal needs constant +12V. You can either tap off the yellow wire, or run a fuse protected wire from either your battery or fuse box.

 

 

ACC -------(red)-->------/Diode/-->-Cap----->relay(coil)------->ground (good idea to use black wire here).

 

Battery/fuse +12v constant ------------relay switch----------(red wire)---------> HU

Battery/fuse +12v constant ------------(existing yellow wire)-------------------> HU

 

Note: Harvey specified a DPDT relay, which is more complicated. In this explanation, I'm using a normally open SPST relay, which only has 4 connection terminals - all of which are used. Two for the coil (trigger) and two for the switched circuit (load).

 

Now, instead of all that soldering and gathering of parts that Harvey designed, you can just buy the device I mentioned in my previous post (PAC TR-7). It does essentially the same thing and more. Being solid-state, it is programmable with various delays. it would be wired:

 

Battery/fuse +12v constant--->>>>>---(existing yellow HU wire)-----> HU

blue TR-7 wire -------------->>>>>---(connect to red HU wire)------> HU

 

ACC ------------------------->>>>>-----green TR-7 wire

(- ground) ------------------<<<<<-----black TR-7 wire

Battery/fuse +12v constant--->>>>>-----red TR-7 wire

 

A simpler explanation:

--cut existing red wire and splice hot end to TR-7 green

--splice TR-7 blue wire to the red to HU (the other end of cut

--connect a tap off existing yellow wire and splice to TR-7 red

--connect TR-7 black wire to ground

 

Note: it would be much easier to program the TR-7 before installing it. Programming it will require a 12v source. Read and follow the rather instructions to program the TR-7 and the delay. Manual: see feature #12. If absolutely required, you can probably do this after the install, but it will require removing power from the red TR-7 wire, and grounding the previously unused brown wire . You will need to be able to see the LED on the TR-7.

 

Hope this helps.

[castellscl]

First, a disclaimer: I never got this to work on my car. It seems that the voltage drop while cranking is too much to keep the HU from rebooting. I think this may be solvable, but I didn't feel like it was worth the effort. Maybe an oversized battery will help. That will have to wait a while since mine is only 18 months old. Another possibility is that my factory radio's constant +12v wire really isn't constant. To test that, I'd have to remove the HU and run a fuse protected wire directly from the battery. Again, not worth the effort at this time. So, the solution here is somewhat vehicle dependent. I'm not sure what level of explanation you are looking for. If you have some background in electronics (even introductory); understand what a diode, capacitor, and relay does, then you should be able to draw a diagram with the info here. You need to deal with polarity issues with the diode and cap. You also need an understanding of how the HU is installed (especially the two power feeds). The HU requires constant +12V (yellow wire) and a switched +12v ACC (red wire) which turns ON/OFF the unit with your ignition switch. The problem we want to solve is that most ignition switches drop the ACC +12v momentarily when the key goes from ACC (or ON) to Start. So this causes the HU to reboot. The solution is to not actually feed the ACC wire to the HU, but to run the red wire to a relay - and through the stored energy in the cap, bridge the short voltage drop (over the red HU wire) for a few seconds until the ignition switch returns to the On position. For this to work, however, the constant +12v (yellow wire) needs to maintain at least 10.8v (minimum operating voltage) while the starter is cranking. Since the original wiring for your installed HU may differ, I'll ignore exactly where the red & yellow wires are connected/fused. Just know that the HU red wire is switched, yellow is constant. What you want is to cut the red wire and run it through: a diode, then a capacitor (which acts like a storage battery), then one coil terminal of the relay. The other coil terminal goes to ground (-). So now we have a short delay before the relay turns off the "switched" circuit. On the "switched" side of the relay, connect one lead to the other end of the red wire to the HU. The other "switched" terminal needs constant +12V. You can either tap off the yellow wire, or run a fuse protected wire from either your battery or fuse box. ACC -------(red)-->------/Diode/-->-Cap----->relay(coil)------->ground (good idea to use black wire here). Thanks, that does help alot. What I was more or less confused about was the directionality of the diode and capacitor with respect to +/- sides and the coil side of the relay. "+ (banded side) to a RS part number 272-1022 capacitor's + side" Banded side is the cathode and -. I guess I'm just not reading correctly or it was a typo on his part. The next part I don't understand is the purpose of that "non-bosch" style relay. Is the attached diagram correct? Battery/fuse +12v constant ------------relay switch----------(red wire)---------> HU Battery/fuse +12v constant ------------(existing yellow wire)-------------------> HU Note: Harvey specified a DPDT relay, which is more complicated. In this explanation, I'm using a normally open SPST relay, which only has 4 connection terminals - all of which are used. Two for the coil (trigger) and two for the switched circuit (load). Now, instead of all that soldering and gathering of parts that Harvey designed, you can just buy the device I mentioned in my previous post (PAC TR-7). It does essentially the same thing and more. Being solid-state, it is programmable with various delays. it would be wired: Battery/fuse +12v constant--->>>>>---(existing yellow HU wire)-----> HU blue TR-7 wire -------------->>>>>---(connect to red HU wire)------> HU ACC ------------------------->>>>>-----green TR-7 wire (- ground) ------------------<<<<<-----black TR-7 wire Battery/fuse +12v constant--->>>>>-----red TR-7 wire A simpler explanation: --cut existing red wire and splice hot end to TR-7 green --splice TR-7 blue wire to the red to HU (the other end of cut --connect a tap off existing yellow wire and splice to TR-7 red --connect TR-7 black wire to ground Note: it would be much easier to program the TR-7 before installing it. Programming it will require a 12v source. Read and follow the rather instructions to program the TR-7 and the delay. Manual: see feature #12. If absolutely required, you can probably do this after the install, but it will require removing power from the red TR-7 wire, and grounding the previously unused brown wire . You will need to be able to see the LED on the TR-7. Hope this helps.

Thanks, that does help a lot. What I was more or less confused about was the directionality of the diode and capacitor with respect to +/- sides and the coil side of the relay. "+ (banded side) to a RS part number 272-1022 capacitor's + side" Banded side is the cathode and -. I guess I'm just not reading correctly or it was a typo on his part. <BR>As for the relay, I can just put a jump across both switch terminals, and another across both common terminals? Is the attached diagram correct?

[Alexei Navalny]

Thanks, that does help a lot. What I was more or less confused about was the directionality of the diode and capacitor with respect to +/- sides and the coil side of the relay. "+ (banded side) to a RS part number 272-1022 capacitor's + side" Banded side is the cathode and -. I guess I'm just not reading correctly or it was a typo on his part. <BR>As for the relay, I can just put a jump across both switch terminals, and another across both common terminals? Is the attached diagram correct?

 

I think your diagram is right. I can't see the marking on the diode, but the banded side should be toward the cap. BTW, I had other parts laying around, and I made up a prototype, which seemed to work when bench testing. I just threw away my diagram on Sunday. I can never remember the diode markings, so I just test with a multimeter to see which way the current flows. Obviously, if it is reversed, the relay wont even energize.

 

 

Sounds like you known as much, or more, about this stuff as me. When I broke one of the leads off my relay during the bench test, , I decided against this DIY approach and when I found the TR-7, I decided "why bother".

Good luck.

[Harvey_Gordon]

Thanks Ron for picking up the gauntlet. I haven't been on the forum too much lately. The PAC TR7 is the way to go. Because it is solid state and programmable, it can do so much more. I am now using this for other things as well. Thanks for finding it. For the price, it's already made up, no DIY required.

 

My system works for me (and I DID run a new fused 12V (and 12 gauge)line direct from the battery to the yellow - so now no rebooting for no reason), but now I wouldn't do it. Thanks for finding the PAC unit.

 

hg

[castellscl]

Thanks Ron for picking up the gauntlet. I haven't been on the forum too much lately. The PAC TR7 is the way to go. Because it is solid state and programmable, it can do so much more. I am now using this for other things as well. Thanks for finding it. For the price, it's already made up, no DIY required.

 

My system works for me (and I DID run a new fused 12V (and 12 gauge)line direct from the battery to the yellow - so now no rebooting for no reason), but now I wouldn't do it. Thanks for finding the PAC unit.

 

hg

 

 

Ok, thanks.

I'll go the PAC route then.

 

Anyone got some more indepth "How-to" on the programing of that thing?

[castellscl]

Ok, after a lot of trial and error, I discovered that I was not supposed to cut the red wire. I just hooked up the blue and green wire from the PAC up to the red wire from the HU. The red wire from the PAC to the yellow of the HU and then the black wire from the PAC to ground. It worked then.

Of course, I did this after programing.

 

I also had to run a constant 12v from the battery to the yellow wire of the head unit.

 

BTW, I have a 2003 Ford SVT Lightning(F150).

[henrya]

I also have the same problem, my HU reboots everytime i start the car, i already bought the tr7 device, now i just need help programming it. I dont understand how to do this. Can someone explain to me how to program the device for it to fix our problem. Thank you in advance, i know that its function 12, but i dont understand how to exactly program it.

[Alexei Navalny]

I also have the same problem, my HU reboots everytime i start the car, i already bought the tr7 device, now i just need help programming it. I dont understand how to do this. Can someone explain to me how to program the device for it to fix our problem. Thank you in advance, i know that its function 12, but i dont understand how to exactly program it.

 

Henry,

I researched the TR7 and was going to install it but I never got around to it. Once I realized that, by itself, it would not solve my reboot problem, I put it on hold . I would also have to run a heavy gauge wire directly from my battery (the yellow power feed) because the voltage drop (during starter cranking) on the factory harness was also a problem. I just didn't feel like ripping my center console again just for this annoyance. I'm waiting for the Z130 s/w upgrade to justify removing the HU and at that time will install the TR7, new Traffic Tuner, better mic, and rear camera.

 

 

I think I understand the basics of the TR7, but I have not actually done it. So, if no one else steps in, I will try helping. Maybe if you asked more specific questions. Are you asking how to set up the programming or are you asking for help with specific parameters? Like what values to use for the time delay?

I think the method of programming is pretty well covered in the manual, but I can see that if you are new to this stuff, it could get confusing.

 

Again, I'd rather have someone who's actually done it respond, but I can take a guess if no one responds. Maybe you could PM some of the members who have used it (see above). They might not see your question if they don't frequent the board often.