: Electrical relay



junny
12-15-12, 03:12 PM
My battery keeps dying. I found out that when I turn off the car relay 51 stays clicking, but i dont know why..can someome help me.

ddalder
12-15-12, 04:17 PM
You need to provide a little more information. What year is your STS? Which engine do you have? Have you checked the Owner's Manual to see what relay 51 is for? Some people post questions here for Pre-2005 cars, even though the forum is for 2005+. This will dramatically change the response.

Cadillac Cust Svc
12-17-12, 11:29 AM
Ddalder is correct -- knowing the model year of your STS would be very helpful! I do recommend checking with your Cadillac dealership, so their specialized technicians can view the concerns firsthand. However, I understand if you prefer the DIY approach. If you would ever like me to look into the matter further for you, don't hesitate to email me at Katie_Lucille@gmexpert.com.

Best,

Katie
Cadillac Customer Service

carter's_sts
12-17-12, 12:59 PM
If it is 2005+ lots of people talk about clicking and whining noises that these cars make. So it may be completely normal. You may just have a bad battery. That's common. They don't seem to last long.

eatyoursandwich
12-19-12, 04:08 PM
I happen to have an old Catera who's battery keeps dying also.

Any ideas???? :bonkers:

EChas3
12-19-12, 09:26 PM
Have the battery load tested. If it's OK, you have a charging system problem.

ddalder
12-19-12, 11:13 PM
Have the battery load tested. If it's OK, you have a charging system problem.
I wouldn't necessarily jump to this conclusion. A wiring problem or module fault can most certainly create parasitic draw and battery failures with no fault in the battery or charging system. It is always important to use a structured approach to diagnosis and repair.

EChas3
12-20-12, 08:48 PM
OK, DD...

Add 'Probably'. or My guess is....

These cars do have protective circuits but still draw a lot more current than many cars do, even when sitting idle. Most accessories always have power and are turned off by the car's network.

ddalder
12-20-12, 10:21 PM
The 2005+ vehicles can have close to 30 different modules, so as you indicate, this can be a problem. I'm thinking about a failure of some type that has increased parasitic draw beyond "normal" levels and that we shouldn't rule this out. Unfortunately, it's difficult because we don't have confirmation from the OP about what car is really being discussed here. As many of us know, first time posters have made the error of asking non-2005+ questions in this forum. The underlying cause may be entirely different in pre-2005 models.

carter's_sts
12-21-12, 01:51 AM
Pretty easy to disconnect a battery terminal and put a current meter in line to see what the stand by current draw is. I don't know what it should be, but if it's excessive it should be pretty obvious.

Anything more than a few milliamps would probably be bad.

ddalder
12-21-12, 04:47 PM
Pretty easy to disconnect a battery terminal and put a current meter in line to see what the stand by current draw is. I don't know what it should be, but if it's excessive it should be pretty obvious.

Anything more than a few milliamps would probably be bad.
Well, it's not that easy. Unless you have or make an adapter for measuring parasitic draw, this will likely be unsuccessful.

carter's_sts
12-21-12, 09:56 PM
I've done it before on other cars. You just need little jumpers with alligator clips, with a DC current meter in line with the battery and the the cable you disconnect. Doesn't even matter which cable.

Any current draw from the battery will be measured. You wouldn't want to start it because you'd burn up the small jumpers, but you can then disconnect anything or unplug any relays or fuses to see where the extra draw (if any) is coming from. Pretty basic DC circuit stuff. All the current flow has to end up back at the battery.

carter's_sts
12-21-12, 10:06 PM
The worst part will be when you jump out of your pants when the alarm sounds when you hook up the battery.

ddalder
12-21-12, 11:13 PM
I understand what you're saying because I am very well versed in DC circuits and automotive electronics/electrical troubleshooting.

My point is that, even in the absence of the horn going off, these cars have enough modules that there will be a relatively high initial current draw when first connecting the battery. Virtually every multimeter I've used has two inputs for current measurement (300mA and 10A). Even using the 10A input, that initial draw will undoubtedly exceed this and will blow the internal fuse protecting the meter. If you've managed to do this in the past successfully, I suspect it was an older vehicle that wasn't as "module endowed" as these cars. If the horn is activated the meter fuse will blow for sure.

The purpose of the parasitic draw adapter is to permit full current to pass enabling the car to power up. The meter will be connected to either side of a switch. At this point, there will be a dead short across the meter. When the vehicle modules enter "sleep" mode, you can open the switch and the meter will now be in series with the negative battery cable. This will allow for the measurement of what should be a relatively small draw and carry on with diagnostic testing.

carter's_sts
12-22-12, 01:05 AM
Makes sense to me. I think if I had blown the fuse in my trusty Fluke 85, I would do what you are saying, but I would just use a jumper wire temporarily across the meter until things settled down.