Power Glitch on Start

[yeloshak]

1996 NSX-T

It is stored most of the time.
I have a battery quick disconnect on the neg terminal so it usually sits with no power. Like for 6 months.
It always starts right up when I reconnect the battery. (Thank you DieHard!)

I get things warmed up, reset the radio presets and the clock and ease out of the garage.

The next time I start the car, when cranking, the radio goes black (as expected).
But when the car starts, the radio stays off. When I turn the radio back on, the presets have been lost and its back to FM 87.5.
The clock time (top of the dash) is preserved.
Right after the car starts, there is a loud relay click, that sounds like it is coming from high in the center console - it clicks twice.
"Click - 0.3 sec - Click". (About as fast as you double click your mouse).

When I turn the car off, if I stop in ACC - everything works fine.

In fact, everything is fine except the radio seems to get "unplugged" whenever I start the car.

Any ideas???


(my apologies if this is in the forum/wiki - I search for 2 hours... )

 

[Old Guy]

The head unit get constant power for the presets via fuse 33 . As long as that fuse is good and there is nothing 'up' with the wiring between fuse 33 and the head unit, you should not lose the presets. If you power up the radio and enter the presets and fuse 33 has blown, you will lose the presets when you power down the head unit (power down occurs during cranking).

The keep alive power for the clock is also fuse 33 . The fact that you are not losing your clock suggests that fuse 33 is OK. But, just for good measure, confirm 33 is OK and if it is then you may have to remove the head unit to get access to the connector at the back of the head unit. Remove the connector and check for unswitched 12 v on pin A4 (wht/yel) which is the keep alive power for the head unit. If you have continuous 12v on pin A4 then something may be up with the head unit - such as failing capacitors.

The keep alive power is directly off of the battery via fuse 33 - no relays involved. The external amplifiers are powered up by a relay which is located in the front in relay box A or box B. If the head unit powered up briefly and then quit that relay would double click; but, you would require very good ears to hear it. I don't deny that you are hearing something; but, there is no relay in the center console associated with the head unit / amplifiers.

I am assuming that your car is stock and that nobody has messed with the wiring?

 

[drew]

Marginal ignition switch?

 

[yeloshak]

Fuse 33 (Clock fuse, under hood) was OK.

I pulled the ignition switch and cleaned it per the Wiki and things are the same.
It looked to be in pretty good condition.

The clicking I am hearing is coming from the tape deck. It seems to click when power is first applied to the radio.

Since the clock is keeping time, the next step I think is to pull the radio and check if there is power to it when the car is off.
Looks like its the Yellow/White wire in A4 if I am reading the schematic correctly.

 

[Old Guy]

It has been a long time since I had my head unit out to clean it up; but, I don't remember any relays in it. I think there was a cassette release solenoid thingy / thing that removes the tape from the drive which could make some clicking noise; but, not obvious to me how that could be related. Just to confirm, when you do power back up everything works fine except that you have lost the presets? If so, then checking A4 seems like the next step.