teamzr1 Posted September 23, 2021 Report Share Posted September 23, 2021 HI All ON the subject of the Power Steering Pressure Switch Having moved to an area where the summer is very hot my 1993 Deville 60 special 4.9L engine On random basis on startup the idle would go nuts and sometimes engine dies No DTCs trip and OBD-I shows all looks good as to fuel trims, MAP, timing etc. So I assumed it was the ISC and replaced it, though this issue then seemed better over some cold starts the problem still exists but happened less. I assumed then it was a thermal issue as the weather went from 100 deg days to low 80s. Used 2 different ECMs, Memcals and calibrations and both have the same issue Car has over 210,000 miles on it, but more about car's age that some sensors are original and get weaker. So I started researching this, and it hit me a weak PSP can cause idle issues It is even labeled as part replacement as : 1993 Cadillac DeVille Idle Speed Control Power Steering Pressure Switch - 10218778 AC Delco - $24.18 I understand testing the PSP with an Ohm meter with steering wheel flat straight will show open and when wheels are locked hard either direction then circuit should then be closed Question is having PSP not fully going faulty but having degraded cause the idle issue ? I did a simple test where on cold start kept the wheels dead straight and idle was perfect around 650 RPMs for good 5 minutes. The began turning steering wheel back & forth (half to full wheel to wheel) and sure enough idle RPMS change. Put the wheels straight, idle fine and again back/forth on steering wheel and RPMS go up and down So where physically exactly is it for 1993 as from engine bay I could not find it ? Is this on the rack and only can be seen/replaced jacking front end up and getting under there and if so, can PSP be replaced without having to take other things out ? I assume being down there then taking PSP off that will lose most of the power steering fluid and when PSP is installed have to add fluid and then bleed the system ? Quote Link to comment Share on other sites More sharing options...
Logan Posted September 24, 2021 Report Share Posted September 24, 2021 Might be mounted on the hose. Quote Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
teamzr1 Posted September 24, 2021 Author Report Share Posted September 24, 2021 Hi and thanks for the reply Is this for a 4.9 L 1993 Deville and is that next to the exhaust pipe, image kinda small so was not sure ? Thanks Quote Link to comment Share on other sites More sharing options...
Logan Posted September 25, 2021 Report Share Posted September 25, 2021 4.9L........#6. Quote Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
teamzr1 Posted September 26, 2021 Author Report Share Posted September 26, 2021 Hi Logan Thanks for the time and effort in getting an image for me. ! Hope this is not too hard to get to be able to replace PSP switch Quote Link to comment Share on other sites More sharing options...
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