Need help! Erratic Dashboard lights

[ede smith]

Video of erratic dashboard

Can someone tell me what’s going on with this 2001 Century? Intermittent issue, Traction off light comes on, service vevichle soon light. Security light and needles on gauges fluctuating. ABS light doesn’t come on. Only code stored is P1860 Torque Converter Clutch TCC PWM solenoid circuit. Don’t pay attention to the low coolant light, sensor has been replaced and there is a TSB from buick on this.

Any ideas what’s causing this and I need to drive out of state tomorrow but am a little concerned as the frequency of this happening has been increasing.

I finally ordered a blue driver scanner so hopefully that will help me in keeping this car in running condition as long as possible.

 

[ede smith]

Video of erratic dashboard

Can someone tell me what’s going on with this 2001 Century? Intermittent issue, Traction off light comes on, service vevichle soon light. Security light and needles on gauges fluctuating. ABS light doesn’t come on. Only code stored is P1860 Torque Converter Clutch TCC PWM solenoid circuit. Don’t pay attention to the low coolant light, sensor has been replaced and there is a TSB from buick on this.

Any ideas what’s causing this and I need to drive out of state tomorrow but am a little concerned as the frequency of this happening has been increasing.

I finally ordered a blue driver scanner so hopefully that will help me in keeping this car in running condition as long as possible.

I went to a shop this morning and they plugged it in to their scan tool and did a short free diagnostic evaluation. Basically they said it’s an electrical issue and requires 1-3 hours more testing at $80-$240 before any repairs can be started.

They think it may be either a bad BCM, bad ground, or something bad in the instrument cluster.

Anyone run into this? Looking for some guidance here. Thank you

 

[chem_man]

How handy are you with a Digital MultiMeter (DMM) and a Logic Probe? FYI a logic probe is similar to a test light, but a zillion times better because it will not damage any sensors or expensive control modules like the ECM/PCM, BCN, etc. You can purchase a logic probe for about $10 at Harbor Freight.

Computer Safe Automotive Logic Probe

Amazing deals on this Computer Safe Automotive Logic Probe at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

The odds are, because of so many different things going haywire, a bad ground is likely the cause. Where is the ground located? That I am not sure, but start with the battery's negative cable and where it attaches to the engine block and to the body (yup, 2 separate locations).

Here is a link to an online Chilton's Manual (several steps above the consumer manuals sold at auto parts stores):

McDowell County Public Library - Chilton Auto Repair

mcdowellpubliclibrary.org

You will need the above link in order to view various electrical schematics to help you track down the problem(s).

Good Luck!

 

[ede smith]

Heres my scan report from bluedriver. Looks like everything is going haywire!

 

[ede smith]

How handy are you with a Digital MultiMeter (DMM) and a Logic Probe? FYI a logic probe is similar to a test light, but a zillion times better because it will not damage any sensors or expensive control modules like the ECM/PCM, BCN, etc. You can purchase a logic probe for about $10 at Harbor Freight.

Computer Safe Automotive Logic Probe

Amazing deals on this Computer Safe Automotive Logic Probe at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

The odds are, because of so many different things going haywire, a bad ground is likely the cause. Where is the ground located? That I am not sure, but start with the battery's negative cable and where it attaches to the engine block and to the body (yup, 2 separate locations).

Here is a link to an online Chilton's Manual (several steps above the consumer manuals sold at auto parts stores):

McDowell County Public Library - Chilton Auto Repair

mcdowellpubliclibrary.org

You will need the above link in order to view various electrical schematics to help you track down the problem(s).

Good Luck!

It looks like I will need to invest in a logic probe. Could that also cause the P1860? Thanks for your reply and help! I finally bought a Blue Driver.

 

[chem_man]

Perhaps. I do not know where the Torque Converter Clutch PWM Solenoid Circuit is grounded.

 

[GentlemanDrinker]

So I just resolved those very symptoms in my 2004 Buick century and found something corrupting the data bus line. After many YouTube videos and trial and error I found that my airbag module was bad(wasn’t even recognized by my $1,200 scanner.). Mine is located under the passenger seat and had corroded over time making the intermittent problem progressively worse. I was able to determine that it was this module by using a wiring diagram and the scanner to determine that the car was supposed to have said module. After locating the module and following instructions on how to disconnect without the airbags deploying. I I ran the scanner again and all the problems were resolved. I do not have functioning airbags at the moment. Repair of the SDM module is $550 and I’m not paying that. Unless I find a reasonable price replacement it will just have to wait. If you are handy with a multimeter and can read wiring diagrams you can back probe the comb behind the DLC and see if the voltage for the SDM wire is correct.


I also used the library link posted above it has a very good step by step guide for diagnosing data bus problems. Also YouTube search GM SERIAL DATA BUS, yours will be the single wire can us the 2 wire with high low came out later.

 

[ede smith]

So I just resolved those very symptoms in my 2004 Buick century and found something corrupting the data bus line. After many YouTube videos and trial and error I found that my airbag module was bad(wasn’t even recognized by my $1,200 scanner.). Mine is located under the passenger seat and had corroded over time making the intermittent problem progressively worse. I was able to determine that it was this module by using a wiring diagram and the scanner to determine that the car was supposed to have said module. After locating the module and following instructions on how to disconnect without the airbags deploying. I I ran the scanner again and all the problems were resolved. I do not have functioning airbags at the moment. Repair of the SDM module is $550 and I’m not paying that. Unless I find a reasonable price replacement it will just have to wait. If you are handy with a multimeter and can read wiring diagrams you can back probe the comb behind the DLC and see if the voltage for the SDM wire is correct.


I also used the library link posted above it has a very good step by step guide for diagnosing data bus problems. Also YouTube search GM SERIAL DATA BUS, yours will be the single wire can us the 2 wire with high low came out later.

Wow, your post is so helpful as I’m still dealing with this problem. I actually bought a body control module (BCM) from a boneyard relatively cheap and was planning to install it, but wasn’t sure if I would have to have the computer reprogrammed at the dealership. I do have a fluke 88 multimeter and need to get more practice with it as electrical diagnosis is my weak area. I also have a friend who is an electrical engineer. I can print out the schematics and I think he’d be interested in helping me solve this problem.

How essential is it to have a real scanner to isolate the problem? Perhaps I can find someone with a scanner to tell me to my airbag module is reading. I don’t have a $1200 scanner but just a blue driver that connects via bluetooth.

Thanks for the YouTube suggestion, I’m gonna look that up for sure

I thought I was an isolated case, and no one else was experiencing the same problem with their Buick. Thanks for the reply and giving me some direction with the repair

 

[GentlemanDrinker]

So I just resolved those very symptoms in my 2004 Buick century and found something corrupting the data bus line. After many YouTube videos and trial and error I found that my airbag module was bad(wasn’t even recognized by my $1,200 scanner.). Mine is located under the passenger seat and had corroded over time making the intermittent problem progressively worse. I was able to determine that it was this module by using a wiring diagram and the scanner to determine that the car was supposed to have said module. After locating the module and following instructions on how to disconnect without the airbags deploying. I I ran the scanner again and all the problems were resolved. I do not have functioning airbags at the moment. Repair of the SDM module is $550 and I’m not paying that. Unless I find a reasonable price replacement it will just have to wait. If you are handy with a multimeter and can read wiring diagrams you can back probe the comb behind the DLC and see if the voltage for the SDM wire is correct.

Wow, your post is so helpful as I’m still dealing with this problem. I actually bought a body control module (BCM) from a boneyard relatively cheap and was planning to install it, but wasn’t sure if I would have to have the computer reprogrammed at the dealership. I do have a fluke 88 multimeter and need to get more practice with it as electrical diagnosis is my weak area. I also have a friend who is an electrical engineer. I can print out the schematics and I think he’d be interested in helping me solve this problem.

How essential is it to have a real scanner to isolate the problem? Perhaps I can find someone with a scanner to tell me to my airbag module is reading. I don’t have a $1200 scanner but just a blue driver that connects via bluetooth.

Thanks for the YouTube suggestion, I’m gonna look that up for sure

I thought I was an isolated case, and no one else was experiencing the same problem with their Buick. Thanks for the reply and giving me some direction with the repair

After looking at the report generated by your scanner it should work fine. It goes into the other modules besides the ones that control emissions.
These are a few of the videos that helped me diagnose my problems. You could also check the voltage at the DLC. I would watch a few videos to make sure it’s something you are comfortable doing.

And if you go to this site (thank you to whoever originally posted this link) go to
BODY AND ACCESSORIES

DATA LINK COMMUNICATIONS

DIAGNOSTIC PROCEDURES

It’s a very detailed step by step process that worked for me. I don’t think you need a $1,200 scanner, I was using this problem to justify buying new toys. I mean tools. The big clue was getting alternator voltage on the can bus it should be no more than 7 volts on a single wire bus.

If you do end up using the ew BCM it will need to be programmed with your cars VIN. I’m not sure how much more programming is needed as I haven’t had that experience yet.

 

[ede smith]

After looking at the report generated by your scanner it should work fine. It goes into the other modules besides the ones that control emissions.
These are a few of the videos that helped me diagnose my problems. You could also check the voltage at the DLC. I would watch a few videos to make sure it’s something you are comfortable doing.

And if you go to this site (thank you to whoever originally posted this link) go to
BODY AND ACCESSORIES

DATA LINK COMMUNICATIONS

DIAGNOSTIC PROCEDURES

It’s a very detailed step by step process that worked for me. I don’t think you need a $1,200 scanner, I was using this problem to justify buying new toys. I mean tools. The big clue was getting alternator voltage on the can bus it should be no more than 7 volts on a single wire bus.

If you do end up using the ew BCM it will need to be programmed with your cars VIN. I’m not sure how much more programming is needed as I haven’t had that experience yet.

Thanks for the videos and folllow up. I will report back as I hope to work on it this spring. Yea the manual with the link has been such a helpful resource, jt has saved my hide so many times. Invaluable really, I Hope it never goes away because so many DIYer’s don’t have another resource like this.

I looked at some of the more expensive scan tools and would be interested in one that had by bi-directional control. They aren’t cheap but along with an Alldata subscription look amazing.

 

[Balsam12]

Did you end up finding the issue? I’m having some intermediate electrical problems aswell. Few times a month all dash lights will blinking very rapidly and many clicking sounds. Battery is brand new. I’m replacing ignition switch to see if that helps. Car won’t crank aswell when issues are happening

 

[ede smith]

Did you end up finding the issue? I’m having some intermediate electrical problems aswell. Few times a month all dash lights will blinking very rapidly and many clicking sounds. Battery is brand new. I’m replacing ignition switch to see if that helps. Car won’t crank aswell when issues are happening

I haven’t had any clicking noises with mine or no crank issue. Read further on down the post and.Gentleman drinker replied with a repair that worked for him. As for myself, I haven’t had a chance to work on it with the cold weather. Good luck

 

[Balsam12]

I haven’t had any clicking noises with mine or no crank issue. Read further on down the post and.Gentleman drinker replied with a repair that worked for him. As for myself, I haven’t had a chance to work on it with the cold weather. Good luck

Thanks. I’m replacing the ignition switch as that seems to be an issue with electrical issues on Buicks. I’ll let you know how I make out with the repair and if that fixes anything.

 

[ede smith]

After looking at the report generated by your scanner it should work fine. It goes into the other modules besides the ones that control emissions.
These are a few of the videos that helped me diagnose my problems. You could also check the voltage at the DLC. I would watch a few videos to make sure it’s something you are comfortable doing.

And if you go to this site (thank you to whoever originally posted this link) go to
BODY AND ACCESSORIES

DATA LINK COMMUNICATIONS

DIAGNOSTIC PROCEDURES

It’s a very detailed step by step process that worked for me. I don’t think you need a $1,200 scanner, I was using this problem to justify buying new toys. I mean tools. The big clue was getting alternator voltage on the can bus it should be no more than 7 volts on a single wire bus.

If you do end up using the ew BCM it will need to be programmed with your cars VIN. I’m not sure how much more programming is needed as I haven’t had that experience yet.

Okay, a friend who is good at fixing consumer electronics offered to help me. Today he brought his scope and the first order of business was finding the data link comb. Once we found that, he back-probed each pin, connected to his scope, and I turned the ignition on to the accessory position. We could not find anything out of the ordinary.

I am wondering when you diagnosed your intermittent problem did you have to have it happen concurrently when you were testing? I have million trouble codes but wondering if we need to catch it as it's happening to see where the problem is coming from. Also, I don't have a $1200 scanner that does bidirectional testing. It's just a simple blue driver blue tooth deal.

I did purchase a junk yard BCM some time ago but from my understanding, the stealership would need to program it. It would be better to diagnose the problem then to just change this part.

Any help is appreciated. Thanks

 

[ede smith]

I am changing the oil today and saw this twisted hanging wire that I have seen for some time. Could this be a suspect?