2000 GMC radio on/off via turn signals

[Jakesdad]

Hello all,

I recently bought a 2000 GMC Sierra 4x4, factory am/fm single cd radio.

Great truck except the radio turns on and off whenever it feels like it. Will work fine for days, then for several days the turn signal switch, or the power lock switch will turn the radio on or off - a good percentage of the time, but not always.

When the radio turns itself off, the cd eject works, and the recall button will display the time briefly, as if the truck is off, but will do nothing else. Hitting any/all of the radio buttons will not turn the radio on, neither will pounding the dash or yelling profanities at it.

 

So far, there is no identifiable pattern to what turns the radio on or off. Is the problem within the head unit or some other GM mystery switch?

 

-Thanks

[GM-Tech]

Whenever there's a bizzare electrical problem, like this one, I start by looking at grounds. Lack of a good ground can cause all sorts of weird behavior.

 

It doesn't seem likely it's the radio itself, though possible. Is there any aftermarket junk in this truck? Pull the radio and see what might be patched into the harness.

[Jakesdad]

Whenever there's a bizzare electrical problem, like this one, I start by looking at grounds.  Lack of a good ground can cause all sorts of weird behavior.

 

It doesn't seem likely it's the radio itself, though possible.  Is there any aftermarket junk in this truck?  Pull the radio and see what might be patched into the harness.

 

<{POST_SNAPBACK}>

 

 

 

Nothing added to the truck - it's all original. Dealer has taken the radio out, checked all wiring to it, all appears fine. Can't identify a problem, so replacing the radio is the dealer's first guess at a diagnosis.

 

A bad ground sounds plausible, the truck also occasionally loses the power portion of the power steering, only momentarily and at parking lot speeds.

Other than the obvious battery connection, where are the other grounds?

[GM-Tech]

here's a listing of grounds on your truck...

 

 

G100

On the left radiator support bracket

 

G102

On the right front of the engine block (4.3L)

 

 

G102

On the left front of the engine block (4.8L, 5.3L, 6.0L)

 

 

G103

On the right rear of the engine block

 

 

G104

On the left rear of the engine block

 

 

G105

On the right front of the engine block (4.3L)

 

 

G105

On the left front of the engine block (4.8L, 5.3L, 6.0L)

 

 

G106

On the right front of the engine block (4.3L)

 

 

G106

On the right rear of the engine block (4.8L, 5.3L, 6.0L)

 

 

G107

Engine to body (engine ground strap)

 

 

G108

Hood to body (body ground strap)

 

 

G110

On the left front body mount behind the left front wheel housing

 

 

G200

On the right upper IP at the A pillar

 

 

G203

On the left upper IP at the A pillar

 

 

G302

On the left body mount

 

 

G304

Under the driver seat

 

 

G305

Inside the passenger compartment on the left side at the B pillar

 

 

G306

Inside the passenger compartment on the right side at the B pillar

 

 

G401

On the spare tire hoist bracket

 

 

G403

On the left frame rail near the body mount

 

 

G410

On the right rear inner side body panel

 

 

G410A

On the right rear inner side body panel

[Jakesdad]

Thanks GM-Tech!

[asilverblazer]

I would try pulling the radio out and putting a test light on it's power souce wire, the switched ignition wire, if the light goes out when locking the doors or whatever the problem is truck related not radio. That is unless my theory has a gaping hole in that I'm not seeing right now.

[Jakesdad]

Update: I had the dealer check the grounds, he assures me they're all o.k.

I installed another radio (used, from similar year truck) as a test. The replacement radio does the same thing, so the problem isn't in the radio.

 

Under the theory that the ground(s) is the problem, I hard wired a ground line from the radio housing directly to the negative battery terminal.

This didn't solve the problem. The radio still turns off intermittently, and hitting the power lock switch or turn signals will either cause the radio to turn on or off, but not when you want them to.

The dealer is suggesting replacing a door switch, $148 for the switch.

Is it plausible that a door switch could cause this phenomenon?

 

I'm close to tossing the factory radio, and installing an Alpine the old fashioned way (no GM computer interference).

[Jakesdad]

Hello all,

I found the problem!

There is a jumper wire somebody (I assume not GM) poked into the fuse panel at the driver's end of the dash that connects the 20 amp fuse for the doorlocks to the relay for the drivers side power lock. The wire had partially crept out of the fuse socket, causing an intermittent bad connection. When the radio would turn off by itself, apparently hitting the power door lock button re-established a connection, and allowed the radio to turn back on.

Removing the jumper wire causes the radio to have no power at all. Reconnecting the wire results in a normally working radio - no more intermitent on & off.

 

I have no idea why the power locks' jumper wire is related to the radio, but apparently it is, at least on my truck... I also have even less of a clue as to why the turn signals caused the radio to turn off, but at least for now, that problem is gone.

 

If somebody can explain to me why the two are related, please do.