RKrautsack Posted April 8, 2012 Report Share Posted April 8, 2012 Ok ....I have a 99 Concours . Purchashed 1 1/2 years ago with 112k now 156k . I've read Extensively about HG and overheating problems and solutions. Temp at 194-196 consistantly. first problem occurred when I jumped on the throttle while pulling out and turning. Temp dash icon flashes, then "engine overheated" then to limp mode. lasts no more than a few second maybe 8-10seconds at the most. i have not done a block test or coolant/exhaust gas test. Coolant Does NOT smell at all of exhaust,no bubbles in overflow tank. This morning I pulled throttle body and cleaned all the carbon (heavy) which was causing thottle stick, high idle. while in the process, I checked and cleaned an unplugged purge line. this "false" intermittent limp mode is ONLY when in gear, only on acceleration from stop, or low-speed turns. This must be electrical... I have definite engine compartment fuse / relay corrosion issues that I've maintained on an "as needed" schedule. Whadaya think is my best course of action. Thanks Randy Link to comment Share on other sites More sharing options...
RKrautsack Posted April 9, 2012 Author Report Share Posted April 9, 2012 And....current OBD II codes are:P0117 ECT Sensor 1 Circuit Low Input; P1258 for the Low Engine Coolant/Fel Disable. I unplugged the ECT Sensor and it stopped, But is that the only part of the system disabled or can it be one of many possible failures Link to comment Share on other sites More sharing options...
Ranger Posted April 10, 2012 Report Share Posted April 10, 2012 I think you found your problem. Replace the ECT sensor. Link to comment Share on other sites More sharing options...
BodybyFisher Posted April 10, 2012 Report Share Posted April 10, 2012 I got your email, I agree with Ranger check your Engine Coolant Temp Sensor (ECT) connections and replace if necessary. 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...
RKrautsack Posted April 14, 2012 Author Report Share Posted April 14, 2012 Thanks for your response guys. I replaced the ECT sensor. still steady spikes in the system triggering limp mode. Problem seemed to be less likely to pop up in todays damp rainy weather?? Would you suggest cleaning and/or replacing the maxi,relay and fuse connectors in the underhood compartment next? Where else should I be checking. I did not mention the engine hot - A/C off has been along for this entire ride heat is not abnormal. I monitored the coolant temp on the OBD-II while driving. Temp. is constant at 194-196 range BUT..the spikes in tempeture all read 304 degrees every time.?? Oh,while installing the sensor I learned its not a great idea to drop the new one. i now have a spare somewhere deep down in the aybss of the "hey , what else can we fit under here" engine compartment. Link to comment Share on other sites More sharing options...
BodybyFisher Posted April 15, 2012 Report Share Posted April 15, 2012 304 degrees? For future reference stop the car immediately when it reaches 260 so as to NOT damage the engine Why are you letting it get so high?, doesn't the STOP engine message come up? Have you checked to see that the purge line is flowing?, if not, you wont get the air out of the system and the water pump will cavitate Have you checked to see if the system holds pressure?, with a pressure test? Is the thermostat opening?, is it binding? 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...
RKrautsack Posted April 15, 2012 Author Report Share Posted April 15, 2012 Not a chance.....Temp spikes are split second.The actual temp never surpasses 196. Purge , Pressure, flow have been done. i believe I only breifly mentioned the purge in my first post. I also have spent time reading these threads with referance to NS cooling/electrical/HG issues. Based on your experience and obvious knowledge I sent you a direct E-Mail asking for your help. I welcome your comments on this problem seemingly unique to this forum. I just ran Diagnosics via the ACB exclusive to the Concours. I'll going be in my next post as soon as I check my notes. Link to comment Share on other sites More sharing options...
RKrautsack Posted April 15, 2012 Author Report Share Posted April 15, 2012 CURRENT PCM... P0420 PZM... B0533 B2473 MMM... B2147 ACM... B1347 Link to comment Share on other sites More sharing options...
RKrautsack Posted April 15, 2012 Author Report Share Posted April 15, 2012 HISTORY PCM... P0116-7, P1114, P1258; ACM... B1350, B1983; SMD U1016, U1255, B1327; RSS... C1738, C1783; PZM... B1552 OBD-II SHOWS PCM P0116 CURRENT HAD RECENT BACKFIRE, Need to know more about BPValve Link to comment Share on other sites More sharing options...
RKrautsack Posted April 22, 2012 Author Report Share Posted April 22, 2012 I don't have a service manual for the electrical aspects. Any links anyone you an suggest? Link to comment Share on other sites More sharing options...
Ranger Posted April 23, 2012 Report Share Posted April 23, 2012 Not exactly sure what you are looking for, but you need to post the code definitions along with the codes. Link to comment Share on other sites More sharing options...
BodybyFisher Posted April 23, 2012 Report Share Posted April 23, 2012 What I would do is check the ECT wiring to see if it is chafed or rubbing against something causing this problem. I have a 91, 94, and 96 factory service manual, not sure if it will help with your 99. Something is causing you to have a low input on the ECT sensor. Correct me if I am wrong but the ECT sensor is on the left side of the engine below the crossover correct? You are sure the connector is tight and the contacts are not loose or corroded?, it is making a solid connection? I can only think that this is related to the ECT wiring or connector 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...
RKrautsack Posted April 24, 2012 Author Report Share Posted April 24, 2012 Heading out now to check connections and look for wire issues. And yes that is the correct position for that sensor. I did replace the sensor and assumed the connection was good. I'll keep you posted.... thanks again Link to comment Share on other sites More sharing options...
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