Humminbird 788ci HD DI issues

I am having issues with the 788ci HD DI I have on the front of my boat. When I turn it on after about 5-10 minutes, it just shuts off. Or when you turn it on it just sits there saying “loading” and never comes on. I thought it was the quick connect and took that apart, made sure there were good connections and it seemed like it worked. Next time out, it did not. So, I thought then it was the actual connection to the power wire. I re-did that connection and last night on the water, it still only worked for about 5-10 minutes and then went off. Thinking it was something internal to the unit, when I got home, I hooked the 788 up to my wires in the back for the 999. Turned it on and left it sit for probably 15 minutes. Stayed on the whole time.

What kind of connection issue would cause the problem I am having? It is hooked up to the trolling motor transducer when in the front? Not sure that could cause any issues like this?

Any thoughts/guesses?

I should add that it worked this spring and early summer. Problem has just started to happen.

Gerty,
Is it fair to say that your first 2 experiments, that resulted in failure, were out on the water, vs your last experiment, with the boat in the driveway/garage and no vibration/movement?

I’m thinking there’s an internal failure as a result of movement. if you lived close to me, you could borrow one of my 788’s and try a different head unit.

HRG

HRG,

You are correct. However, last night it was dead calm on the water. I do not think vibration was an issue. Head unit also is in the truck on the way out to the lake so no road vibration on the way out.

I suppose I could take my quick connect apart and use the wires to hook up my 999 up front and see if there is any issue with that as another test?

Everything just has me leaning towards an internal issue just can’t prove it as of yet!

BTW, I am in Mankato.

Gerty wrote:

HRG,
BTW, I am in Mankato.

Well, I’m near Chicago IL, so that probably won’t work. I’d put up a posting and see if you could borrow a 788-size unit, so you use your existing base, connectors and wiring.

There’s got be be a bunch of guys up by you who still use these units.

HRG