Weird electrical issue/s

[96-2D-Hoe]

Hi,

I have a weird electrical issue, or two, with my 96.


1) Couple times I've had a relay going nuts under the dash to the left of the brake pedal somewhere but nothing seems to be affected. This always happens while driving so I haven't found it. I've rummaged around trying to move what might be a short and nothing changes, it just stops on its own. This was the first thing and I've heard it a few times over the past 2 years or so.

2) Weird fluttering noise, not very loud, seems to come from behind the headlight switch / vent. Nothing seems to be affected. Probably first noticed about a year ago

3) Factory radio has cut out a few times, even when not on recently. I've seen the time go blank a few times when it's been off. Probably noticed this about 6 months ago.

It's a low mileage Southern California truck that has never been off-road (I know!). There is no corrosion anywhere. I've checked a couple earths and they are spotless. I do have an aftermarket alarm that was fitted about 4-5 years ago.

The radio has done it's thing a couple times when it's been raining but otherwise there's nothing that I'm aware causes any of this.

Any ideas would be much appreciated.


Edit
4) I've suspected fuel pump as it's a little noisy, and it failed/was replaced about 8 years/10-15k miles ago. But this could also be related. Truck has cut out at idle a couple times recently. First time it ever happened I left it running outside UPS store for 3 mins, came back and had died and then didn't want to start for a couple mins. Then started up fine. I think for a moment I didn't have any dash lights, but I was having issues with the ignition key barrel that was stuck and wouldn't turn. Since then it cut out on me once more at idle, and cut out on the alignment guy twice while he was moving it. I've felt like it has a weak idle sometimes and has wanted to die almost. Haven't checked fuel pressure as I have no gauge.
I've also felt for a long time that the power delivery isn't consistent. Sometimes it goes like the wind and others like a 22 year old truck. I've thrown a couple parts at it over the past few years but nothing has made much difference. But in general it drives pretty well with only 105k on the clock.
One other unusual thing is that a couple times recently it idled at 700rpm when it is always normally at 600. It has no codes. Passed CA emissions last Sept, has never failed.

Just bought a fuel pump this week so I have one. But haven't changed it yet.

Hope someone has some ideas. Throwing parts at it gets expensive.

 

[SnowDrifter]

When you have a multiple symptom electrical issue like this: Find commonalities and look there

Things like a shared ground would be a good place to start. Will wait for someone else to chime in on appropriate info in regards to that

 

[Big Mama]

Water might be a good clue too. Check where water gets into your engine compartment and see if any is getting behind the dash via door seals. Agreed on common ground do you have a wiring diagram to see if they trace to the same area?

 

[96-2D-Hoe]

I don't have a wiring diagram for the truck but it would be very useful. Have worked on AC electrical control systems etc but have no experience with auto electrical.

I've read through 30-40 pages of posts and found some diagrams for parts of the audio system in other posts. There was only one post about the radio cutting out that sounded similar to mine and there was no resolution posted.

I've been working on the truck a lot lately and am always looking for possible wiring issues wherever I'm working. I'm 6'1 and it's not easy to get under the dash but have had a look around a couple times. I keep meaning to trace into all the alarm system wiring but I already had a quick look for obvious issues.

I'll edit the first post but probably should have added some other gremlins as the truck has cut out a few times at idle lately too.

 

[drakon543]

my 97 had a radio that would act up on occasion. most of the time i just wouldn't be paying attn and notice my station had changed or my cd got ejected from the aux drive. i was meaning to replace it anyway for aux connection. i ended up buying a jvc or something on the cheaper end but not at the bottom and has been fine. as far as your fluttering noise ive read the blend door can do that.

 

[Big Mama]

You should be able to find a wiring diagram on line free but in the meantime put a napkin or paper towel above the driver side kick panel and check it after a rain. I had an aftermarket alarm on an older truck that gave me fits. If you don’t use it daily can you unplug it to see if things improve?

 

[96-2D-Hoe]

It seems unlikely to be the radio itself. It's losing power somehow even when turned off.

I've read about blend door actuator but afaik it's not behind the drivers side vent and that's where the noise comes from. Was thinking there is a fuse panel right there and that's about where the noise comes from.

I've never noticed any water getting into the truck. But I'll check again. My most likely cause of a short could be a trailer hitch cable attachment but I can't imagine how that would affect the radio.

 

[east302]

Mine (98, same truck actually down to the color) has a rapid relay-like clicking sound coming from the left half of the dash. It’s when it is first started and driven. It seems to correlate to turning and applying the brakes like when you’re leaving a parking lot.

It’s annoying as hell, so I’m hoping you find a solution. I thought it was the shift lock solenoid because it was pretty loud, but that wasn’t it.

There’s just nothing really under there that I can see. Maybe it’s a relay in the ‘convenience center’...that gray panel down by the parking brake pedal:

Here’s the diagram for the radio, fuse 19 is the power for the memory.

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[96-2D-Hoe]

I think it is in the convenience center, perhaps above it or maybe on the back of it? I've put my hand down there while it's doing it and tried to feel for the relay but haven't been able to feel anything. Mine has only ever done it 5-10 x. Last time was about 4 months ago. I'd even try swapping a relay or two out but it might be a while before I know if it's worked. It sounds like you could find that relay easier than I could if you can recreate it east!

My back isn't great and maneuvering myself under the dash isn't easy. I also rarely get enough space to work on the truck and can only do so when the neighbor is out and not parked next to me. I should probably pull out the drivers seat. I'm sure the motor mechanism could do with a dog hair removal, clean and grease up.

Thanks for the help.

 

[96-2D-Hoe]

I had a better look at the convenience center today. Should have looked at the diagram first, or printed it as I didn't know what I was looking at. There's really not much there. I will take a closer look with the mirror but I don't think there's anything on the back of the convenience center, so it's one of the two relays or the audio alarm module. Which is what I thought it most likely to be when I didn't know what it was. Part of the reason for that is I think I've touched the two small relays while mine's been doing it and haven't felt anything. But the audio alarm has openings on the left side which could be why I think the noise is coming from a slightly different spot where there is absolutely nothing.

There are also what looks like two small relays in the drivers side fuse panel.

If you can make yours chatter it can't be that difficult

 

[east302]

I think you’re on the right track, I’ll try removing the relays one at a time and see if it changes. There are only three to chose from, so it should not be too hard to figure it out.

I’m not sure what the fuse box relays are powering, but that’s worth looking into as well.


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[96-2D-Hoe]

Yeah, it will be why the relay is going nuts. Unlikely to be the relay itself.
Here's a couple fuzzy pics. The audio relay is missing from my convenience center

 

[96-2D-Hoe]

Did the fluttering thing today and I managed to pull over. Coming from somewhere totally different to what I thought. Guessing it is the blend door actuator? A roundish thing to the right of the accelerator pedal if that's what it is. But was doing it while the fan wasn't on.

Edit
Just looked at a blend door actuator on rockauto. I think that's it.

 

[east302]

Blend door actuator...

The silver dial rotates as the dampers are positioned. If it’s hunting back and forth, that could be your issue.


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[96-2D-Hoe]

Thanks. Seems you've been there before

It's just making a weird noise. Should it still be operating while fan is off?

Edit.
Even still. I'm not 100% that's where it was coming from. As it wasn't doing it continually

 

[96-2D-Hoe]

I'll pull the plug on it next time I hear it.

Is the factory amp around there? Something (big silver thing with heat dissipation fins) was hanging right next to it that looked like it should been secured. I need to take a better look with a flashlight and some glasses.

 

[east302]

The dial should only rotate when the air flow position is changed from the panel. There are three indicator marks on the plastic, roughly at 10, 12 and 2 o’clock. The notch in the dial will rotate between those marks.

I want to say that the two door doesn’t have the power amplifier. I looked for one before and never found it in mine.

The manual has these location diagrams for it.

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[east302]

Not sure what it is, but the finned silver thing on mine is above the red/white/blue wires in upper right. Maybe that is an amp, it kind of matches the location in GM diagrams.

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[96-2D-Hoe]

Damn it's nice and clean under your dash. Thanks for the info, I think it might be the amp. No fins though, must been distracted by the daytime running light module. Amp isn't secured very nicely. After looking at the pics it's pretty obvious why.

Loads dog hair in the blend actuator assembly. Could definitely at very least use a clean up/dehairing. Will try that.

Just tried to take a couple pics, not very well though.

 

[96-2D-Hoe]

Sorry, should read posts and not just look at pictures. The finned silver thing is the daytime running light module. I know because I changed it already.