Intermittent Dash Lights/Gauges to Zero

bfairweath

Original poster
Member
Oct 20, 2013
95
Neenah, WI
My '03 has had this happen a few times recently - ABS, Brake, and Air Bag light comes on, all four gauges on the right side of the cluster drop to zero. It's done it on startup as well as after a few minutes of driving. I have a Blue Driver scan tool. It does show some Class 2 network comm failures. I've cleaned a number of the ground points, tried (unsuccessfully) to change to my backup ignition switch (might be shot from riding around in the glove box for 6 years).

I've watched all the videos and read all the posts about troubleshooting the Class 2 network. It just doesn't seem like I have a node that's dying and taking down the network. It's very intermittent. Hasn't happened in about five days. I can still communicate through the OBDII port while the condition is happening.

Weak battery? The battery is old. It seems to crank okay. Here's what's got me thinking that - problem showed up last week when it was in the 30's here in WI. It's in the 70's this week and hasn't happened.

Ignition switch? I did buy a new one to try.

This is my wife's DD. She's already demanding a new vehicle. If I don't make this problem go away quick, it might be the end of the TB. Dealer said they'd give us $683 on a trade in. Thanks.
 

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TJBaker57

Member
Aug 16, 2015
2,897
Colorado
My '03 has had this happen a few times recently - ABS, Brake, and Air Bag light comes on, all four gauges on the right side of the cluster drop to zero. It's done it on startup as well as after a few minutes of driving. I have a Blue Driver scan tool. It does show some Class 2 network comm failures. I've cleaned a number of the ground points, tried (unsuccessfully) to change to my backup ignition switch (might be shot from riding around in the glove box for 6 years).

I've watched all the videos and read all the posts about troubleshooting the Class 2 network. It just doesn't seem like I have a node that's dying and taking down the network. It's very intermittent. Hasn't happened in about five days. I can still communicate through the OBDII port while the condition is happening.

Weak battery? The battery is old. It seems to crank okay. Here's what's got me thinking that - problem showed up last week when it was in the 30's here in WI. It's in the 70's this week and hasn't happened.

Ignition switch? I did buy a new one to try.

This is my wife's DD. She's already demanding a new vehicle. If I don't make this problem go away quick, it might be the end of the TB. Dealer said they'd give us $683 on a trade in. Thanks.


That does look like a loss of serial data. There is a gray data wire from the data splice pack under the left end of the dash up to the cluster. Unless the underdash area has been disturbed though I wouldn't expect that wire to be any trouble. The connector at the top of the cluster maybe. Or the cluster itself. Truthfully I am just guessing here though.
 

bfairweath

Original poster
Member
Oct 20, 2013
95
Neenah, WI
Yes, you're correct. I have an additional generic Bluetooth OBDII interface for Torque. I should have explained better. I was able to communicate with both/either while this condition was happening.
 
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Mooseman

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Dec 4, 2011
25,257
Ottawa, ON
Did you check the battery connections? That can cause weirdness too.
 

bfairweath

Original poster
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Oct 20, 2013
95
Neenah, WI
I had the negative on and off several times when I was messing around with my spare ignition switch. Didn't really check the positive. I'll take a look at that.
 

mrrsm

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Sketchy 10 Amp Fuse in Slot #24 of Power Distribution Center...or the Slot itself? Can't hurt to pull it, Clean the Tangs, Spray out the Slot with CRC Electrical Contact Solvent... and Plug it back in.
 
Dec 5, 2011
574
Central Pennsylvania
Also, check for LOOSE fuses... I had a heck of a time with a single loose fuse.
 
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Mooseman

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Dec 4, 2011
25,257
Ottawa, ON
And corroded fuses and contacts.
 
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bfairweath

Original poster
Member
Oct 20, 2013
95
Neenah, WI
Here's a update. It's been about week since the TB has misbehaved. Went on a 350 mile trip this weekend. Everything normal. One big difference between this past week (everything normal) and the week before (intermittent dash lights nearly every day) is the temperature. It's been in the 70's this past week vs. the more normal 30's-40's the week before.

What do you guys think of my weak battery theory? Could it be causing this behavior? Colder temps = lower battery efficiency = electric gremlins. We've supposedly got one more day of 70's then back to the 40's on Tuesday. Again, it seems to be cranking okay, but the battery is old - maybe 6-7 years.

There may be some credence to Mooseman's suggestion about battery connections. I put my meter across the battery terminals. The voltage readings are very erratic with the truck running or shut off. There is no visible corrosion. Going to try reading just the battery with the cables disconnected tomorrow. I could occasional get a good, steady reading with one meter probe on the positive post of the battery and one on the ground point right behind the battery.

Note: my meter is good. Reads steady 12.6 on my other car as well as my lawn tractor.
 

Mooseman

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Dec 4, 2011
25,257
Ottawa, ON
At that age, that battery owes you nothing and I would change it just on age and to eliminate it as a possible source of these issues. Good time to clean the connectors too.
 
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Mektek

Member
May 2, 2017
656
FL
I don't think it's a battery issue. I have a old battery and while the voltage drops to 9.6 when cranking it still starts OK and the instrument panel works normally. In a northern climate a replacement would be needed, but here I can eke out a few more months of use.
 

Redbeard

Member
Jan 26, 2013
3,466
I have a old battery and while the voltage drops to 9.6 when cranking it still starts OK and the instrument panel works normally. In a northern climate a replacement would be needed, but here I can eke out a few more months of use.
Many years ago I would do the same thing-eke out a couple of more months until I toasted an alternator that had been pushing out to much amperage and died. I believe it cost me about $170 for the alternator on that truck vs about a $50 dollar battery. (this was probably 25 years ago on a nissan p.u.) I didn't think that was too cost effective. An older battery will try to take all the alternator can push out causing it to stay excessively warm shortening it lifespan of the alternator considerably. Especially if it is pumping out at 100% of it's rate 100% of the time. Since then I have purchased a DC amp-meter to see how much the alternator is pushing out electrons.
 
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Mooseman

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Dec 4, 2011
25,257
Ottawa, ON
:iagree:
These trucks are sensitive to voltages. If they're off or the battery is dying, it can wreak havoc on the electronics. And it WILL eventually leave you stranded.
 
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bfairweath

Original poster
Member
Oct 20, 2013
95
Neenah, WI
At that age, that battery owes you nothing and I would change it just on age and to eliminate it as a possible source of these issues. Good time to clean the connectors too.
Good point. I have to test my theory tomorrow through Friday. Temps will be normal for WI this time of year. If it misbehaves - new battery this weekend.
 

bfairweath

Original poster
Member
Oct 20, 2013
95
Neenah, WI
Okay, so much for the weak battery theory. Truck behaved all week in cold temperatures. Maybe Mooseman hit it with a battery connection. It really hasn't misbehaved since I had the negative post on and off several times while messing with the ignition switch two weeks ago. I say "really hasn't" because the TB is my wife's vehicle and she said that the dash lights came on for about a minute after she started it the day after I messed with ignition switch. Yes, I asked if it was the normal light check at startup and she said definitely not. She's not the best at diagnosing abnormal behavior (of a vehicle anyway).
 

bfairweath

Original poster
Member
Oct 20, 2013
95
Neenah, WI
Another update - truck misbehaved a couple of times this past week on some of the colder mornings. I broke down and put in a new battery this morning. There was quite a bit of corrosion on the positive post. I was also wrong about the age of the old battery. When I took the box off, I discovered it was about to have it's 8th birthday. Not smart to go into a WI winter with an eight year old battery - electrical gremlins or not.

I can now get a constant voltage reading with my meter across the posts. I could not before. That may have been a symptom of the corrosion on the positive post. It's a constant 14.78 volts with the engine at idle and no accessories on.
 

bfairweath

Original poster
Member
Oct 20, 2013
95
Neenah, WI
Okay, it's not the battery. It misbehaved once this past week. Yesterday, I checked all the fuses and relays is both fuse boxes. Had some time to kill in the garage while the turkey was in the fryer. Now, it misbehaved three times while my wife was on a 10 mile errand this morning.

I attached the report from BlueDriver that I ran when she got back (the phenomenon was not happening while the scan was in progress). This seems to be pointing to the BCM. Do we see these go bad?

I don't have much time left with this thing. Wife is freaking out.
 

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Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
An individual module might be killing the network traffic and all the other modules freak out when it happens. The trick is finding the offending module. That or there is a short on the network somewhere. What sucks is that it's intermittent.

BCM's are quite robust and haven't seen too many of these fail, maybe just once or twice on here.

@TJBaker57 is our SME in this area and may be able to give a course of action on how to track it down.
 

TJBaker57

Member
Aug 16, 2015
2,897
Colorado
That Bluedriver report seems to confirm my initial thought, you have a serial data line issue. Every heading indicates a loss of communications, several referencing the cluster.

It doesn't help that Bluedriver appears to alter the actual data received, saying things like "shared address module codes" as a heading. There is no such thing. Codes are stored in physical modules with unique addresses! So we are left to try to guess what Bluedriver is reporting there. Like that first code, B2961. The key in ignition switch signal wire goes solely to the BCM. Not connected to any other module and is not shared, and that code is only stored in the BCM.

Something to keep in mind,,,, that same single wire connects to every module. Whatever one module sees, every module sees. What affects one module affects all modules. This makes it hard to point a finger at one module vs another. Also, it is hard to resist that tendency to want to jump to a conclusion that it is a bad part/module. It is just as possible that it is a wiring issue and not a module at all.

Other than the key in ignition signal fault the one that stands out is the U1301. That sets when the serial data line is high, ~12 volts for few seconds (can't remember the specific time period). I have seen that code myself from time to time. Cannot say if it is a frequent visitor to my vehicles or not and my vehicles are not a good representation of the general population as mine are subject to endless fiddling and experiments.

So the problem I see here is being an intermittent it may be difficult to pin down. My approach would be to have a look at and record whatever freeze frame records are available for the history codes looking for clues thay may lie there. Then clear those history codes from all modules and see where they reappear. It would require scanning immediately after clearing and also scanning frequently without seeing any visible indicators of trouble, not waiting for a warning light or such.
 
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bfairweath

Original poster
Member
Oct 20, 2013
95
Neenah, WI
I'm not sure if BlueDriver supports freeze frame data at the time of a code. It has a freeze frame function, but it looks like it just reads a couple hundred PID's on demand, not stored at the time of a code. I will try scanning more often to try to catch something before the thing goes into a full on freak out. I did scan it right after clearing all the codes this morning. Nothing there. I took it on a about a 10 mile trip and scanned again. Nothing there.

Do you happen to know where to find splice pack 205 and 206 on an '03? . They aren't in the same location of the YouTube Class 2 troubleshooting video referenced here a few times. I think that was a far newer TB. The service manuals have wiring diagrams for an '02 and an '04 - no '03. I'm guessing nothing changed between '02 and '03.

Thanks for the help. I figure I've got about a week to figure this out before my wife demands a new vehicle.

EDIT: BlueDriver's documentation says that the Freeze Frame mode will retrieve stored data at the time the CEL comes on. Unfortunately, the CEL doesn't come on with this problem. Maybe it will still record something with the U-codes that are being set. I'll try it.
 
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TJBaker57

Member
Aug 16, 2015
2,897
Colorado
As far as I know the forward splice pack has always been under the left side of the dash above the kick panel. I think originally it is secured with a plastic push pin type attachment. Mine had been left loosely hanging by a previous owner. I found there was enough wiring for me to reroute the thing up behind the headlight switch where I can access it by simply popping off the left end dash access panel.

The rear splice pack is beneath the carpet under the right rear seat. There is usually seen a flap of carpet that can be pulled back to expose the splice pack.
 

budwich

Member
Jun 16, 2013
2,027
kanata
It seems your wife has the magic touch for getting the thing to act up.... is she doing anything... setting fans speeds, temperatures, windows, heating on seats, AC, opening windows, opening the lift gate before the trip..... driving like a maniac and braking the same way..... :smile:
IF the codes are meaningful (correct), it is likely that somewhere along the bus structure / connection you are getting a "short to voltage" for a period of time.

I would start with one of the "usual suspects"... the lift gate module, unplug it for now. I think you will lose your remote feature so ensure that your key works on the door to be safe.
 

bfairweath

Original poster
Member
Oct 20, 2013
95
Neenah, WI
Here is the rear splice pack on my 2002...
Ah, the passenger side. Found it. I was thinking it would be near the fuse box.

Have there been any other issues, even seemingly unrelated nuisance issues? Door locks, keyfobs, etc?
My wife has mentioned once or twice that her fob wouldn't unlock the doors (of course, I couldn't reproduce this behavior), but that was way before this phenomenon started happening. She hasn't reported it since it started happening.

It seems your wife has the magic touch for getting the thing to act up.... is she doing anything... setting fans speeds, temperatures, windows, heating on seats, AC, opening windows, opening the lift gate before the trip..... driving like a maniac and braking the same way..... :smile:
IF the codes are meaningful (correct), it is likely that somewhere along the bus structure / connection you are getting a "short to voltage" for a period of time.

I would start with one of the "usual suspects"... the lift gate module, unplug it for now. I think you will lose your remote feature so ensure that your key works on the door to be safe.
Funny you should mention that. I had that discussion with her this morning. I asked her to be cognizant of anything she's doing right before it happens - so much as tuning the radio. She swears she's just driving along.

I'll work on unplugging the lift gate module tomorrow. That seems like a good thing to do considering she's reported instances of the key fob not working.
 

budwich

Member
Jun 16, 2013
2,027
kanata
NOTE: the unplugging of the module may only stop a fault module from corrupting the bus... the LGM has been known to fail. However, it is more likely that the wiring going to the module is your culprit because the wiring get brittle and breaks from lifting and closing the gate so you need to pay attention the wiring area in general.
 

bfairweath

Original poster
Member
Oct 20, 2013
95
Neenah, WI
TJBaker57 and Budwich, you guys are wise. Went on a 10 mile trip this morning. No lights. HOWEVER, I did a scan when I came back. There was a code for Class 2 network failure (U1000) - and it came from the Door/Gate Module (at least according to BlueDriver). I unplugged the LGM. Now, it seems to be setting a U1000 every time I start it, but BlueDriver now says is a shared code. Could it be that it's just recognizing the LGM isn't there on startup? I clear the code and scan again (without shutting the truck off) and there is no code. I've repeated this procedure twice.

I pulled apart the rubber boot at the top of the lift gate to look at the wiring. After pulling some gray electrical tape off, found that the heavier gauge orange wire has three cracks in the insulation. I don't think the wire is broken. I checked voltage from the plug to ground. I have battery voltage even while jiggling and bending the orange wire.

I'll be going on another 10 mile trip in a couple hours. I'll scan and clear codes on startup, then scan again when I get home.

In case anyone is wondering what is with all these 10 mile trips, I'm running my teenage son back and forth to school for basketball practice. He gets his license in about two months so he can run himself.

EDIT - there's good continuity on the blue wire (which is the Class 2 network wire, I believe) between the plug at the top of the lift gate and the plug at the LGM.

1606580728597.png
 

bfairweath

Original poster
Member
Oct 20, 2013
95
Neenah, WI
Scanned codes on startup. U1000 was there as a "shared address". Went on another 10 mile trip. No lights. Scanned when got home. No codes. LGM unplugged for all of this.
 

TJBaker57

Member
Aug 16, 2015
2,897
Colorado
What Bluedriver might be calling a shared code could be a code that appears on multiple modules. I think all modules can set the U1000 code in their respective memories.
 

bfairweath

Original poster
Member
Oct 20, 2013
95
Neenah, WI
Had to try it. I plugged the LGM back in to see if the start up U1000 would change back to Door/Gate in BlueDriver's categorization. It did not. It still comes up as "shared address."

The "tester" is out of town for the weekend. I'm going to let her drive it into next week with the LGM disconnected and see what happens. Looks like you can get a used LGM off Ebay for about $25. All that needs to be done to when replacing the LGM is to run through the FOB programming procedure, correct? No dealer VIN programming?
 

bfairweath

Original poster
Member
Oct 20, 2013
95
Neenah, WI
Can't drive with the LGM disconnected (at night anyway). The interior lights don't shut off.

Edit: never mind this one. Can shut them off at the dash
 
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bfairweath

Original poster
Member
Oct 20, 2013
95
Neenah, WI
I was laying in bed thinking about this problem last night, tossing and turning at the prospect of having to drop close to $30K on a new (used) SUV. I just wasn't comfortable with the LGM being the problem.

If I may get on my soapbox for a minute. This may help others with troubleshooting in general.

"Occum's Razor" came to mind. I'm guessing MRRSM knows what that is (that's not a knock. You seem very well educated. I enjoy reading your posts). Also, anyone that's seen (and remembers) the late '90's Jodie Foster/Mathew McConaughey sci-fi movie "Contact" might remember. Occum's Razor basically states that given two equally plausible explanations, the simplest is most likely correct. What's the simplest cause of electrical gremlins on a GMT360 and many other GM products of this era? - The Ignition Switch.

The evidence:
  1. The BlueDriver report I posted above had a code for B2961 - Key In Ignition Circuit Malfultion. TJBaker57 called this out.
  2. Why does this always happen to my wife and I can't reproduce it? She has a tendency to try to break some sort of speed record when turning the key of the TB even though I've told her many times over the years to turn the key very slowly and gently due to the failure tendency of the ignition switch. I've always turned the key gently when I drive the TB. Probably got something to do with buying new ignition switches no less than 5 times over the last 17 years.
  3. As stated - the simplest cause of electrical problems on a GMT360 is an ignition switch.
I mentioned that I tried to change the ignition switch to my brand new spare in my original post for this problem, but couldn't get it to work. I decided this morning that I was going to give it one more shot. I lined up the teeth exactly to the old on and it worked (I knew they had to be exact, but I got it down to the mm this time). I should mention that my old switch was the upgraded style with gray cover. It's been working for better than 10 years. I had many switch failures before the new style came along.

Why do I think this might be it? - no post startup U1000 code! It's the one thing I've done that's changed the behavior.

I'm not confident enough to say "that's it" quite yet because of the very intermittent nature of this problem. I think it's got to go at least two weeks without a problem before I call it fixed.

I guess the reason for the long post, no matter if this is the solution or not, is to share my experience how quickly you can get yourself into the weeds of complex solutions to a problem. If I would have stayed focused on the simple things, this problem might have been solved a month ago. I'm almost embarrassed to say this - I actually ordered a new ignition switch from Amazon when I couldn't get my spare to work a month ago. I returned it shortly after I got it because I was so sure that wasn't it.

Thanks for listening. I'll report back one way or another.
 

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