OT: Cadillac CTS

Friend of mine is bringing by his 04 Cadillac CTS in the morning.

It has developed 2 problems, not sure if they are related.

First problem is the horn stopped working. I haven't looked at it, don't know if it still signals the remote lock, but will not work from the wheel. Does the signal from the wheel go through the ECM? Or is it wired directly to the horn relay?

The second problem, something is up with the charging system. Intermittent message on the LED screen, it alternates between "service electrical" to "service charging". It may go several days and not show the message, then do it several times in a row. The battery is staying up. There is no volt meter on the dash, it's built into the same LED screen, but goes away when the error message comes up.

Does this sound like the alternator? Strange that it comes and goes, most alternator failures I've seen are sudden and don't fix themselves...

Any ideas? Like I say, I haven't looked at it, checked any connections, done the usual diagnosis. I'm just afraid I won't be able to catch it in the act, don't want to needlessly replace the alternator.

Anyone seen this before?

Thanks!

check the pigtail at the alternator. iirc the gray wire is the sensor. it may be corroded or frayed. you may want to replace the pigtail, cut thw wire a couple inches back. napa can get the pigtails from dorman.

On some cars wasn't the horn not working a signal that something else was not working, like lights??

Begin with checking the fuses.

No Dash lights meant no tail lights.

I will second checking all fuses. Also battery and alternator connections. Without a FULL scan toll it might be real hard if it is not some thing simple. The majority of the stuff including the horn is operated by the body controller. So you can have an issue with it. Also the car is getting the age where ground issues can cause big troubles. Google the exact issues your having and see what comes up.

On my wifes' Impala, the horn quit working, Also the door chimes, and the "low fuel" dinger. (Light still comes on, but no ding.) Was told the problem is a short in the air bag area, in the center of the steering wheel. Probably stay that way. I believe the fix was 350 just for the part.

Also, I checked all fuses.

I would "scan" it first and see if any codes come up.

I had a t-bird with battery trouble. It would go dead if it sat for awhile. The horn didn't work. It turned out to be the horn relay.

I worked on a Chevy full sized conversion van for a brother-in-law once. He said the battery would go down if it sat for a few days. He also didn't tell me the whole story.

After several hours of trouble shooting, I found the horn relay had stuck. BIL had unplugged the horns to get them to stop but the relay was still stuck and running the battery down. Replaced the relay, plugged the horns back in, and no more problem.

You need a full function scan tool to start. Nothing on that car is direct wired. I would have to look in Identifix, but the horn is likely controlled by the Dash Integration Module, DIM. You are right, the first step will be to see if the horn works when remote locking, or setting off the alarm when the doors are locked. If the horn works then, you have narrowed it to the column and the wiring between it and the DIM. If no horn, swapping the relay with another is about all you can do in the dark, because it is a module issue or wiring between the DIM and the relay at that point. With a full function scanner, like my Modis, all out puts can be cycled to see what is not working.

The charging system is a function of the ECM, and somewhat the DIM, on that car, and the ECM is a semi failure prone part on that car, although not being able to remove the key or no crank is the primary indicator of ECM trouble on those cars. I would recommend a redundant ground wire from the ECM case to ground, even just to stave off eventual ECM failure. The CTS is also almost impossible to get a good reman ECM, they only fail hot, which is a test the rebuilders don't do, so good luck.

Just a suggestion for the alternator problem. Check the serpentine belt tensioner, if it's stiff and starting to seize up it can leave belt loose sometimes causing poor/no charging.

Sprint 6 is correct.

OEM Horn:

TAN (-)

GRAY PLUG AT DIM ***

*** DIM (Dash Integration Module) is found under the glove box.

Questions like these show up on a tractor website when the vehicle owner refuses to use a dealer service department. Good luck.

I worked in GM parts back then. There is a reason they called those the CTS Caddy That SUCS !

Wonder if that is the one with the antifreeze cooled alternator ?

Catera it's predacessor was JUNK and the CTS was not much better ! Good Luck with it.

This site is a bit cheaper and someone just might be able to help. TDF

Most people on here don't like to use a stealer service department, tractor or other wise.