power goes off to HB 400 ID

Seems like good place to ask.
Got a 1987 16' Bass Tracker, three phase motorguide foot control trolling motor, HB 400 ID, with transducer on trolling motor. Problem when I power up the trolling motor the depth finder gos off, comes back on soon as the trolling motor power is off. Depth finder, initializes when first turned on, but does not when this is occuring with the trolling motor, comes right back on with no delay. What is a fix ? Figure I will have to find a different power source. Has anyone else had this type problem to occur and fixed it?

Sounds like a wiring or battery issue to me. I'd get them on different batteries if you can. I'd start at the source though, the battery. To me it sounds like your trolling motor is drawing too much power, or again the battery could be bad.

I might be way off on this, but I hope not. Also, is the trolling motor fused?

Probably not your problem but will offer this.
A while back I ran across a big boat wake and took a good slam down, knocked out my GPS, but, came back on later.
Ever since, it has been intermittent on/off.
Could sometimes jiggle the wires and it'd come on, then off, etc.
Got to be, it would not come on at first, later it would come on, and remain on the rest of the trip.
Finally got off my duff and started tracing my 12V down.
Found it on one side of the fuse but not the other (fuse=good). Took fuse out and found contact on end of wire corroded, cleaned and stretched the spring, all works fine now........

Get the power connection off the TM battery will probably fix your problem but also check for bad/loose connections. If a those are good have the battery load tested.

Just a guess here, but since it is not initializing, I would think this is interference from the TM. I agree with IBN... if you have the unit wired to the same battery as the TM is, change batteries. Nothing but the TM should be on the TM batteries.

I would think that the reason it not initializing with each return is that it is not losing all power but just enough to shut down the display. I'm sure at one time it worked the way it is hooked up now and should work again. While a separate battery would be ideal, you need to start at the present battery and check and clean each and every connnection up to the troll motor and fishfinder. Oh and of course a battery check is definitely in order.

"gene"

Thank you all for your input. Will be off tomorrow, plan on trouble shooting. Will probably change power source to starting battery. I think the boat has one fuse block with just about everything running off of one power source. Since the plug for the fish finder is a cigarette lighter type plug I have a feeling they may have spliced into the trolling motor wireing at the bow. I sometimes have trouble with the plug staying connected. May get a two pole plug when I re-do it. By the way, I do have a new battery I have not put on yet, but the last fishing trip the trolling motor had plenty of power when used. Out of curriosity I may put the new on just to see if it makes a differece. Will post what I find out.

Was the Battery. Put on new battery works great.

Glad you figured it out.

For future reference, the trolling motor should be the only thing on the trolling battery. Everything else should be on another battery. Trolling motors tend to put out some funny interference sometimes.