I think my new head unit is bad, sanity check?

Discussion in '6.9L IH & 7.3L IDI Diesels' started by F350camper, Jun 18, 2017.

  1. F350camper

    F350camper BOOST!

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    Ok fellas I need a sanity check on my new head unit / radio for the truck. I think its bad.

    Issue - it loses all the settings, and the clock resets every time I START the truck. It will keep the settings if I just turn the key all the way off take the key out, have a beer, and then put the key in and turn it all the way back on without starting it, but as soon as I crank it, it resets.

    What I have done to troubleshoot.
    I ran a totally separate wire from the battery to the 12v constant (yellow wire) and the issue still happens.
    As a double check, when I disconnect this dedicated wire from the battery, it also causes the unit to reset and lose all the settings.

    Old head unit worked fine, I just got this one for Bluetooth.

    I think the new one is either bad or just too sensitive to voltage drop on startup.

    Am i missing anything? Both batteries are newish and in good shape. Truck turns over fast and starts fast.
     
  2. shawn deere

    shawn deere So many wrenches, so little time...

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    Could hook up a batt charger and start it. Maybe voltage is dropping too low.

    Maybe clean the grounds from your batteries to the frame also?

    That is a head scratcher tho
     
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  3. BrianX128

    BrianX128 Supporting Member Supporting Member

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    So if the +memory wire was somehow switched in the adapter with something else...

    Only thing I can offer is when I helped dad put his new head unit in his 97, this also would happen when he started his truck. But it also happened if he shut it off. The memory + wire was somehow switched to some wire that did nothing.

    Have you tried to find the memory + wire and make sure it is always on? Maybe yours can't save the stations without that wire having power, and it doesn't when the key goes go "start" somehow but still has "enough" power cycling though the head units capacitors when they key is off because nothing is drawing on your electrical system?
     
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  4. shawn deere

    shawn deere So many wrenches, so little time...

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    Could also be starter pulling more than it should
     
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  5. IDIoit

    IDIoit MachinistFabricator Supporting Member

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    I always have my memory wire directly to the battery. you need to unplug it, run a meter on the constant and watch the voltage when you start it.
     
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  6. F350camper

    F350camper BOOST!

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    Hmm poor ground is something I haven ruled out. I'll run a temporary ground direct to the battery just to see.



    Yeah I have it direct wired to the battery at the moment.
     
  7. F350camper

    F350camper BOOST!

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    Ill give this a try. (sorta the same thing the other Brian was suggesting) I wish I still had my analog fluke, easier to see stuff like this than digital.
     
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  8. laserjock

    laserjock Rebuilding! Supporting Member

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    Yes, I don't like my dmm for this type stuff or checking resistAnce. Need to get a new one.
     
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  9. laserjock

    laserjock Rebuilding! Supporting Member

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    Odd you mention this. My brake controller seems to know when the truck starts but it's not actually tied to any key on source.
     
  10. F350camper

    F350camper BOOST!

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    for those that were curious of the outcome on this. Head unit is going back to amazon.

    Voltage on memory wire never drops below 10.5V while cranking.
    I ohm-ed out the ground from the connector to the battery post at 2 ohms.
    I also ran a temporary ground directly to the post (just for something to try), with no change.

    Long story short, its dropping the memory at 10.5 volts. In reading online, it seems like 8V is where most of them lose it.
     
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  11. jwalterus

    jwalterus Made in America

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    Just to mention, Alpine requires a minimum 10ga memory wire direct to the battery to get enough power when cranking, says so in their manual.
    Theirs WILL lose memory if you use a 12ga wire, ask me how I know................
    You never said what brand you had put in.

    Did you have a soldered connection on your memory wire? If you used a crimp connection maybe it's just loose......
     
  12. junk

    junk Full Access Member

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    10ga on a memory wire. That's hard core. Most of the radio wiring in dashes is like 14 or 16 gauge at best.

    Yeah I wouldn't of thought 10.5 would be an issue either.
     
  13. F350camper

    F350camper BOOST!

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    It was a JVC. I don't think it's an issue with the brand, ive had lots of luck with them over the years.

    Connections were soldered to one of the pigtail adapter kits. At first at least, by the end the memory wire and ground were run directly to the battery.
     
  14. madpogue

    madpogue Full Access Member

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    This illustrates a common difference between factory and aftermarket radios, at least factory radios of our vintage. Way back in the olden days of manually-tuned radios with no clock, there was no need for a memory wire. Just a switched power source. With the introduction of electronic tuning and built-in clocks came the need for two power wires, one switched and one unswitched. So they just added an unswitched circuit that draws a teeny tiny bit of power for the memory.

    A lot of newer aftermarket radios turn that on its head. That is, the main power for the radio comes via the unswitched circuit. The switched circuit is only used for power on/off triggering. Unfortunately most '90s-era vehicles are wired with BIG wiring for the switched circuit and small wiring for the unswitched, which is the exact opposite of what newer head units need. I used to be on a Saturn forum (old wagon is still sitting in the far back of the driveway), and on the old S-Series this was such a major problem that the added power draw of an aftermarket radio unswitched circuit would melt a critical connection in the interior fuse box.
     
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  15. jwalterus

    jwalterus Made in America

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    This is important.

    THINK about it.....
    Your truck had what, maybe 20 watts peak from the factory radio? Possibly 40 if you had a 4 channel?
    Most aftermarket radios are at least 200 watts (50x4), and my current radio is 300 (75x4).
    Are you going to run a 300 watt amplifier for a subwoofer on a dinky little 14ga power wire?
    Cripes, makes me want to go run 4ga to my radio just thinking about it...... LOL
     
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