mistermau Posted October 11, 2006 Report Share Posted October 11, 2006 Morning Folkz. New issue with my 97 STS. I fixed the FPR issue, and that's working great so far! This morning I'm riding up the street, and the "Service Engine Soon" light comes on. I get to my friend's house, who I am taking to the airport, and my parking brake won't disengage. Luckily I know how to do it manually, because of that time my battery died while I was on this steep hill. Anyway, I get home, and check codes. The only thing I get is a MSM B2120, which is something about the memory seat. This doesn't surprise me, because it has been a bit fidgetly lately. I cleared the codes, so we'll see what comes back. The parking brake is still an issue, though. What could be causing this? I haven't been driving the car lately, my wife has been driving it. I'm pretty sure she uses the parking brake most of the time, though. Is this a simple vacuum line that has pulled off? Is this something I can reconnect? Help?!?! -Mau Link to comment Share on other sites More sharing options...
BodybyFisher Posted October 11, 2006 Report Share Posted October 11, 2006 Assuming that you don't have any vacuum hose issues, (check if your HVAC system cycles through heat, ac and defrost locations), then there is a vacuum servo motor on the parking brake assembly. See this thread posted by Scotty, (I posted a photo of the vacuum servo motor): http://caddyinfo.ipbhost.com/index.php?sho...;hl=servo+motor Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
mistermau Posted October 16, 2006 Author Report Share Posted October 16, 2006 Okay. I have more info now. (I don't get into the car as much as I used to, since my wife started driving it.) At any rate, it looks like I MAY have a vacuum hose issue. We hopped into the car yesterday headed to a wedding, and since the car had been sitting in the sun all day, it was a bit warm inside. The only place air would come from was through the defrost vents. So, exactly what is a vacuum hose issue? Is this something that I can fix myself? $$? Here's the kicker: could this cause the P0171 AND P0175 codes to appear? I'll continue to dig through the archives, but don't let that stop you from responding! -Mister Mau Assuming that you don't have any vacuum hose issues, (check if your HVAC system cycles through heat, ac and defrost locations), then there is a vacuum servo motor on the parking brake assembly. See this thread posted by Scotty, (I posted a photo of the vacuum servo motor): http://caddyinfo.ipbhost.com/index.php?sho...;hl=servo+motor Link to comment Share on other sites More sharing options...
BodybyFisher Posted October 16, 2006 Report Share Posted October 16, 2006 The P0171 and P0175 are fuel trim codes. There is a vacuum supply on the passenger side of the engine. You will see a check valve and a T. There is a nylon tubing that goes from that area down to a vacuum tank under the passenger side head light area. If there is a leak in the tank, fittings or hoses you will have HVAC and parking brake release problems. Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
mistermau Posted October 16, 2006 Author Report Share Posted October 16, 2006 Okay. Is this something that could have been caused by rough handling while putting things back together after changing out a starter? How do I find the leak? Thanks! The P0171 and P0175 are fuel trim codes. There is a vacuum supply on the passenger side of the engine. You will see a check valve and a T. There is a nylon tubing that goes from that area down to a vacuum tank under the passenger side head light area. If there is a leak in the tank, fittings or hoses you will have HVAC and parking brake release problems. Link to comment Share on other sites More sharing options...
Ranger Posted October 16, 2006 Report Share Posted October 16, 2006 Is this something that could have been caused by rough handling while putting things back together after changing out a starter? Possibly. How do I find the leak? Start by locating the cabin vacuum supply line where it enters the cabin at the firewall on the passenger side. If it is unplugged, you've found the problem. If not, unplug it and see if it has vacuum at idle. If it does, then the supply is good and the problem lies in the cabin under the dash somewhere (check the parking brake release line first). If there is no vacuum at the supply line at the firewall, then the problem is under the hood. Trace the line back and find the leak. It could be a disconnected line or cracked reservior. Link to comment Share on other sites More sharing options...
mistermau Posted October 20, 2006 Author Report Share Posted October 20, 2006 HHHmmm... Does anyone have more guidance on finding the spot on the firewall where the vacuum supply line enters the cabin? I removed the panel under the glove box, and all I see is a jumble of wires and such. I did see the lever that moves back and forth as the AC vents are "supposed" to be opening and closing. I was able to make the lever move by operating the "location" button. Does this help in the diagnosis probem? -Mau Is this something that could have been caused by rough handling while putting things back together after changing out a starter? Possibly. How do I find the leak? Start by locating the cabin vacuum supply line where it enters the cabin at the firewall on the passenger side. If it is unplugged, you've found the problem. If not, unplug it and see if it has vacuum at idle. If it does, then the supply is good and the problem lies in the cabin under the dash somewhere (check the parking brake release line first). If there is no vacuum at the supply line at the firewall, then the problem is under the hood. Trace the line back and find the leak. It could be a disconnected line or cracked reservior. Link to comment Share on other sites More sharing options...
BodybyFisher Posted October 20, 2006 Report Share Posted October 20, 2006 See Firewall for entrance point, the T, and the check valve in this photo of my Deville. Check the rubber hoses for cracks and porosity. One of my hoses was porous. The feed comes off the engine, goes to the T, the T breaks off THROUGH the FIREWALL, and to the TANK (Drawing details entire system with tank) What I did was to use a vacuum gage and hand pump to check the tank and associated nylon tubing. The tubing can crack and wear through. I just replaced the tubing to the tank, it is located near the accessories and can be damaged by debris or bad serp belts. Make sure the fitting at the tank is good. I have a new fitting if you need it. The check valve could be cracked, but if you loose your HVAC going up hills, a bad (one way) check valve can cause it. Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
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