QuestionHi, I’ve got a ’92 Cadillac Seville STS 4.9L and I’m getting some diagnostic trouble codes:
E040 current – Power steering Pressure Switch : don’t know anything about it
E052 history – PCM memory reset: I assume this is from disconnecting the battery
E091 current – PRNDL Switch problem: this was replaced a few years ago with the transmission
Any help with what the problem could be and/or how to fix it would be appreciated
I am also having some electrical problems with the cooling fans and the AC compressor. one cooling(pusher) fan was getting power but no ground, so I ran a direct ground and now that one is working. The other fan(puller) is getting ground but no power. The ac compressor is not getting power either.
Another problem(i know, there’s alot) while im driving at speeds above 40 or 45 mph, and I let off the gas and get back on it the engine just shakes and it will quit when I pump the gas pedal a few times. I don’t know what is up with this?
Thanks for the help
AnswerHi Danny,
Ok...lets go down the list.
E040: Most likely a defective P/S pressure switch that is screwed into the rack. If you remove the electrical connector there should be ignition voltage at terminal B with the key on or engine running. Then hook up your ohmmeter leads across the switch and with the engine running turn the steering wheel lock to lock. The meter should show continuity and then open as the wheel is turned. If it stays the same all the time that means the switch is bad.
E052:You are correct.
E091: Cadillac has had problems in the past with those switches. If the switch is out of adjustment that will set the code like if someone forgot to put their foot on the brake and tried to move the shifter. There is a test in the Caddy manual that by going into on board diagnostics you can see if the switch is showing the correct code for each shifter gear position. The switch could be bad.
The cooling fans can be commanded on using on board diagnostics or a professional scan tool that way you can test to see where the problem is. Also you will need a good wiring diagram. There are several relays that power the fans and maybe the relay is defective. or the computer might not be able to energize the relay to send power to the fan.
The a/c compressor diagnosis starts with a pressure check of how much freon is on the high and low side gauges. It wouldn't surprise me if there was a leaking evaporator core and the freon level was too low to allow the compressor to turn on. Could also be a defective relay for the compressor since you didn't mention and other codes.
Your last problem could be that you just need a complete tune-up with cap, rotor, plugs, wires, ignition coil and a fuel filter. If those haven't been replaced in 50,000 miles that might do the trick. Also knowing what the fuel pressure is when driving would be a big help. What I do is get a fuel gauge with a long enough hose and tape the gauge to the windshield with duct tape. Then when the problem is acting up if the gauge reading is low then you need to trouble shoot the fuel system starting with a fuel filter replacement. Pull off the hose at the fuel pressure regulator to make sure the diaphragm doesn't have a hole in it. You don't mention a rough idle but you could have several injectors that are shorting out and as the engine warms up it will run rougher and could cause the engine to quit. Lastly the fuel pump could be weak and need to be replaced.
If you are going to do the diagnosis work yourself then get a factory Cadillac shop manual...ebay motors is a good source if you have 2 weeks to wait. Otherwise subscribe to All-Data and you will have the correct info that you need available at your home computor and can be printed out and taken to the car. Hope that helps. Bill
