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6K views 24 replies 8 participants last post by  El Dobro 
#1 ·
Ok, I'm new here and want to start by thanking anyone who contributes useful information.

99 Cadillac STS - current behavior: Start car and some or all of the following occurs without a pattern that I can see ...

1. Service Airbag Message
2. Service Security (I might be off on the wording here.)
3. Gas Guage reads empty (even tho it's not)
4. Radio works, then doesn't, then maybe does etc ...

Note that the car is running fine, however I am hesitant to drive in current
condition as the Stereo has on occasion Popped really loudly and I don't really want the speaks to get smoked.

Recent events leading up to current behavior:

1. Passenger Window regulator fell apart (plastic pully disintegrated). Since window was left in half open state, I removed inner door panels (which required unplugging all harnesses in the Pass door). I "manually"
closed the window and left the inner door panel off so I could run for the short term. At this point no problems with dash.

2. Ride for about 2 weeks, no problem ... then Service Airbag followed by
miscellaneous dash symptoms as enumerated at top of this message.

3. Take to my mechanic who replaced window regulator. He says that he
was advised to remove the battery cables and touch them together to (without battery contact of course) to discharge all capacitors in computer.
He did that and the dash wierdness disappeared. I'm smiling.

4. Rode car for about 15 miles, and now I'm not smiling ... Dash wierdness has reappeared.

In addition to any helpful commentary, I am interested in knowing:

1. How do I "ask" the computer for diagnostic reports?
2. What module would be suspect given the behaviors I've described?
3. Where exactly is that module?
4. Is it user serviceable in the sense that I can remove and ship to have
repaired or replaced?
5. Is is it likely coincidence or did my running the car with the passenger door absent for so long cause my current problems?
 
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#3 ·
I bet your going to need some help.

All the computers and radios etc talk too each other on the Class2 data network. Works great...untill some component goes bad. Then ALL the computers start acting weird.

Chances are you will have mutiple 'loss of data' type codes in basically all the modules. The trick will be finding the 'one' bad one messing evrything up.

Logan
www.airbagcrash.com
www.logandiagnostic.com
 
#4 ·
Big thanks for the responses.

Steps taken since last post
------------------------------
1. disconnect battery
2. loop negative to positive cables for a couple hours

Car is presently acting fine, but I am not convinced all is in check.

Here is the script as of now ...

ABS U1301 / C1255 / U1255
NO AMP CODES
DDM U1161 / U1301 / U1255 / U1066 / U1064 / U1016 / U1065
DIM U1301 / U1255 / U1065 / U1016 / U1066
IPC B1652 / B1656 / U1301
IPM B1652
IRC U1301 / U1129 / U1064 / U1065 / U1160 / U1016 / U1144
PCM P0603
RFA U1255 / U1300
RIM U1301 / U1255 / U1064 / U1160 / U1096 / U1065 / U1016
SDM B1163 / U1300 / U1301 / U1096 / U1064 / U1016 / U1040 / U1255
VTD U1016 / U1064
MSM B1900 / B2355 / B2365 / U1000 / U1305 / U1160 / U1064 / U1016
TTM B1983 / U1300 / U1255 / U1160 / U1064 / U1016
NO RSS CODES

Does look like a short occured and wacked the net. Curiously it appears
to be an intermittant situation and I am wondering if the case is that a wire
is shorting on occasion that it wacked the communications. If that's the case I'm looking at bright side that no "damage" has been done. My intuition leads me to believe that a "damage" condition would always fail. Am I deluding myself?

Next step suggestions? Clear the codes and run? watch for recurrent codes?

I am really hoping to at least get a narrowed down speculation of whats wrong so I can decide to go with my mechanic, or better to go to dealer and avoid my mechanic shipping the wrong components out for diagnosis.

Again gratitude to those who take the time to assist.
 
#5 ·
Umm...with that many codes....theres a problem on the Class 2 data network. So...yeah...we were correct.

I just grabbed one code...

DTC U1300 Class 2 Short to Ground
Refer to Data Link Connector (DLC) Schematics

Circuit Description
The class 2 serial data line communicates information between the modules. Each module connected to the serial data line is assigned a recognition code, or address. This code is used in order to identify which modules are communicating. Modules communicate with each other by periodically sending state of health (SOH) messages. When the ignition switch is in RUN, each module that is communicating on the serial data line sends an SOH message every 2 seconds. This ensures that the system is operating properly. The module also monitors the serial data line for short to ground. If the module detects a short to ground for more than 3.0 seconds, the module stores the class 2 Bus Shorted to ground DTC U1300.

Conditions for Setting the DTC
The module detects that the class 2 serial data line is shorted to ground for at least 2.6 seconds.

Action Taken When the DTC Sets
DTC U1300 is stored in the memory module.
The module uses the default values for any information needed from the other modules on the class 2 serial data line.
This DTC does not cause a driver warning message to appear.
Conditions for Clearing the DTC
This DTC clears (status changes from current to history) when the module detects the class 2 bus is not shorted to ground.
A history DTC clears after 50 consecutive ignition cycles if the conditions for setting the DTC are no longer present.
Current and history DTCs may be cleared manually by using a scan tool.
Diagnostic Aids
This DTC is not received as current because the class 2 serial data line does not function during this condition.

Test Description
The numbers below refer to the step numbers in the diagnostic table.

Inspect CKT 1807 (PPL) for intermittent shorts to ground.

Clear all DTCs after you complete the repair.

I dont think you will find it with the onboard cluster diagnostics....you will have to find someone with a Tech2.

This one happens to be ours:

http://images.andale.com/f2/115/106/3768672/1056786545085_tech.jpg

Have fun....

Logan
www.airbagcrash.com
www.logandiagnostic.com
 
#8 ·
When starting the car, it was cranking a little slow like the battery was going. Before I had a chance to change it, the dash started going nuts. The gauges would go wacky then settle down. After that, all the warnings in the DIC started popping up and I mean all of them. They started reading out one after another. I went into diagnostics and it was filled with codes. I figured that before I got into it, I would change the battery since it was over 5 years and I was having the starter issue. I changed the battery and ALL the problems went away and have not returned since.
 
#9 ·
Spoonman,

Did you try replacing the battery? I just had a similar experience happen.
After a stratup as I put the car into drive and started to roll all of a sudden the TC and security light came on, followed by service air bag, service suspension system and the chime started to ding. I put the car into park and stut it off. Started it back up and nothing. All lights and messages were off and had no problems since.

After checking the on-board diagnostics, I got the collowing codes (ALL HISTORY): I had checked the codes about 3 days before-usually do it once a month-and there were non stored in any of the modules.

Anyhow here they are:

ABS: C1298, U1016, U1056
AMP: U1301, U1064
DDM: U1066, U1064, U1065, U1016
DIM: U1255, U1065, U1016, U1066
IPM: U1064, U1016, U1066
IRC: U1229, U1064, U1065, U1160, U1016
PCM: P1602, P1064, P1611, P1612, P1613, P1614, P1615, P1626
RFA: U1305
RIM: U1064, U1160, U1065, U1016, U1096
SDM: U1301
VTD: U1016, U1064
MSM: U1305
TTM: U1300, U1255

No other codes in any other modules.

Please let me know if it resolved after replacing the battery.

Thanks,
David
 
#10 ·
Padosd ...

Have not yet replaced the battery. I am considering it though. Did you replace your battery and problems resolved for you? Or have you not yet done anything? Are you in a 99 STS? if not, what?

I am curious to see if the battery was your answer. I am wondering if I should just throw this at the dealer, but if it's just the battery, then that would be a shame to waste the dough on a service call.

Please let me know if you did the battery, also interested in knowing if your symptoms reoccur or not (before replacing the bat)

Thanks! :)
 
#11 ·
spoonman449 said:
Padosd ...

Did you replace your battery and problems resolved for you? Or have you not yet done anything? Are you in a 99 STS? if not, what?

Please let me know if you did the battery, also interested in knowing if your symptoms reoccur or not (before replacing the bat)

Thanks! :)
Spoonman...

It is a 99 STS with 85,500 Kms. Original 5 year old battery. I have not replaced the battery, because the problem did not come back. Have been driving it for about a month and a half and everything is fine. (I pulled two codes today without ever experiencing anything out of the ordinary. A U 1255 in DIM and RIM module) I have connected for the first week after the incident a voltmeter into the cigarette lighter (accessory) and the readings were all within parameters. Voltage drop during crank was down to 11.8 V and while driving was 14.1-14.3 V.

Did your problem reoccur?

Regards,
padosd
 
#12 ·
Oh yeah. It's regular behavior at this point. Not happy. :hmm: Like I said ... I'm considering the dealer at this point just to get it dealt with rather than play the deal with it myself game. I thought it worthwhile to at least toss the issue to the forums to see if there might be someone with same experience and resolution. I will let you know what I find out once this is resolved.
 
#13 ·
Haven't replace the bat. But I did go back into my passenger door just to give all the wiring harnesses a once over. I'm suspecting an intermittant ground. So now my problems have left again. But I'm prepared for them to come back. I hate this one. Comes and goes. What I'd like to do if it comes back is eliminate the door circuitry temporarily since I'm suspicious that it's in that area. :banghead: :banghead: :annoyed:

I wonder if the "trunk" of wires goes to a plug in the dash where I could do that. If anyone reading this knows what I'm talking about, would be cool to know if that's the case and if so how to break into the dash to find that plug so I can disconnect it for a while and see what the outcome is.

I'm insisting on this troubleshooting style since I'd like as much reproducibility as possible before I turn the dealer loose on a mega hour goose chase for an intermittant problem.

Thanks to all.
 
#14 ·
Several people have said they have seen these multiple codes come up because of a 'bad' battery.

Rather than start 'shaking wires', in this car with a complex electrical system, why haven't you removed the battery and taken it to a parts house and let them do a load test on it? Then you will know about the battery....

Of course, Cadillacs are also known for problems with the battery cables, especially the positive one. This is the second place I would check. If the battery has leaked and eaten away at the battery cable ends, this could be the problem.

Now the positive cable - this is about $500 or more at the dealer. It connects to the starter, which is inside the intake manifold, so there is significant labor for a replacement. But if just the cable end is eaten up, an independent shop could probably replace just the end for a nominal charge. (I would guess a Cadillac dealer would not do this type of repair on a cable, they would require you replace it.)
 
#16 ·
LCLCLC said:
Several people have said they have seen these multiple codes come up because of a 'bad' battery.
Am I missing something? I've only read one case of a known bad battery. (El Dobro's)

Padosd is wondering about his battery but does not yet know for sure.

Please let me know if the several people you mention are outside the scope of this thread and I'll look there! Thanks! :)
 
#17 ·
Well, its clear you are having Class2 data errors.

El Dobro brought up a very good point. A old/crusty original battery can cause bizarre problems just like you describe.

On a '99. If it has the original battery....it would be pushing being 5 years old. Cadillacs are sensitive to having good batteries in them.

Try replacing the battery. If its 5 years old it on it last legs anyways. Could have a bad cell or plate in it.

Logan
www.airbagcrash.com
www.logandiagnostic.com
 
#18 ·
Ok, I'll do the battery. I was holding off as starting power seems strong so I was reluctant to believe that's the real problem.

You are right, for short dough it at least cuts that part of the equation out.

BTW Padosd - I will keep you posted as to whether or not it fixes the prob since I realize you are wondering about your case as well.

Thanks to all for your input - this forum stuff is awesome. :D
 
#20 ·
"1. Service Airbag Message"

"the Stereo has on occasion Popped really loudly"

"4. ... Dash wierdness has reappeared."


I replaced the ignition switch on my 99 STS due to similar problems.

I was having all sorts of funny things happen during startup. My ABS and Traction Control idiot lights would come on intermittently and then they would, for no reason, shut off and occaisonally come back on again after driving.

Also, I would sometimes have a hard time starting the car. Upon running diagnostics, there was always a multitude of communication-related history codes. As it turned out, this ignition switch has a bunch of contacts in it. At least one of those contacts "makes" the serial data communications circuit that communicates between all of the onboard processors.

When I pried the old ignition switch open, I saw that at least 3 of those contacts had arched enough to cause a bad contact points - kind of like worn points in an old distributor-type ignition system. So sometimes when the car was started, there would not be a good connection when the contacts pulled in. Other times it would be fine.

Upon replacement of this switch, all problems went away. It has been over a year since replacement.

I don't know if this is your exact problem, but it may be something to consider.

Good Luck

Todd
 
#22 ·
Well ... let's see ... 3+ years later and here is where this one stands:

The dashboard freaking out was clearly due to a weak battery. That is the good news. For those of you out there with a freaking out dash, DEFINITELY get your battery right first, the computer wants it's power and if it's the slightest bit weak, you will get all kinds of misleading display.

What I still have is a "parasitic" leak while the car is parked ... so what that means is if I leave the car parked for 24 - 48 hours. I start it and I either get a blank dash and unpredictable conrol response from the climate control or a
pinball machine like lightshow on my dash.

So check this out, for the last 3 years my "routine" with this car is to disconnect the battery every time I park so the voltage stays hi enough to satisfy the dash computer. Oh the irony, such a nice car and yet the epitome of anti luxury.

I am hungry for any creative thoughts on chasing a parasitic leak. I am wondering if I can "divide and conquer" by disabling certain circuits by pulling the fuses and watching for the guilty section?

Oh and check this ... I paid $600 to the dealer to chase this one down only to have them come back and ask approval for more diagnostic time. I pulled the car since I felt these guys were less capable than myself.
 
#23 ·
I do have one suggestion:

Check and make sure your retained accessory power isn't staying on after the car has been parked and the door(s) opened. This happened on my mom's 97 Deville. Normally, it only stays on for 10 minutes after engine off, or until a door is opened (whichever comes first)

She would park the car, battery would be drained to non-starting capacity overnight. Looked at it myself and found the radio, power windows, compass rearview mirror etc. all stayed on even after a door had been opened. I spent 3 nights chasing this one, had the back seat out checking connections/harnesses and probing for voltages at the electronics bay. Then, I discovered the problem under the hood in the fuse block/relay center:

The cheap A$$ relay that controls the retained accessory power had been internally corroded by moisture damage such that the contacts were stuck closed. Verified by switching with another identical relay (there are a few in there that are the same, just pull and swap). This cured it, I went to the dealer and bought a relay and it hasn't been a problem since.

I hope this does the trick for you.

KDirk
 
#24 ·
Thanks KDirk

I have been watching the RAP cycle and things seem ok most of the time, although I notice sometimes the DAMPER relay is left on for hours!!! ?? problem is it is intermittent which complicates the troubleshooting path.
Thanks for tip on relay swap.

I have continued the story at this thread, if anyone would like to contribute to this discussion, please do so at this thread ---> http://www.cadillacforums.com/forum...um/110670-battery-leaking-while-parked-5.html

Thank you all!!
 
#25 ·
The Seville went nuts on me one day. The alarm went off, the dash was flashing and the gauges were moving around, the interior lights stayed on, etc. I worked the remote and started the car a few times until everything settled down. The next day, I had the battery checked and there were a couple of bad cells, so I replaced the battery on a prorate. It's been ok since, so these cars must be extremely sensitive to any battery problems.
 
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