I have a 1998 U 270 that has a issue with the oil pressure reading. When the vehicle is at operating temperature at an idle it will peg the reading, when driving at highway speed it reads around 22 PSI, If the headlights are turned on it will loose about 4-5 PSI, and the engine temperature will increase by about 10 degrees. The oil sending unit and the dash guage have both been replaced, it seems like the guage isn't grounded properly, other owners have said they have similar problems but no one seems to have an answer for this. I know 30 PSI is the minium this 325 HP Cummins is supposed to have, I believe the guage is just not reading properly, but I want it to work properly. Thanks................. JD
Hmmmm. Is your engine an ISM with ecu, or mechanical 8.3? My 1999 36' U-270 with ism was notorious for inaccurate coolant temp readings. Replaced most of stock senders, gauges, etc. Read ecu, history showed never had been above 195 degrees since new. Gave up, bought vmspc, put on ancient pc I left in coach. Loads of data, ignore dash gauges (confirmed they were flaky btw) and lived happily ever after.
Not sure if 1998 has ism or ecu.
Yes, probably a bad ground. You can run a jumper connector with alligator clips over from a ground point to the gauge to make sure. Good indication of problem when you turn the headlights on. Check all grounds, starting with the batteries and work forward. Would solve problem before you drive much as you are receiving erroneous engine information. Other members with same model may have also had the same problem. Do you have the schematic for the electrical system? Sometimes these may take a while to find. If you feel you don't have the level of expertise to do it, get a helper that does. Sorry, you may be Mr. Electrical but had to ask.
Would also put a digital voltmeter from the ignition solenoid case (ground) to the hot terminal and also to a hot fuse on the house battery side. Would check reading with engine off, idling and at 1200 RPM or so. Will give an indication of a good ground at the solenoid and charging system health.
Any problems with the turn signals blinking too fast or a dim headlight? Any other abnormalities no matter how small?
Most likely the dash light inverter is going bad, check wiring diagram A-6465, if you do not have this diagram go to Barry Beams site, under technical help look for dash light inverter, Dash Inverter Diagram (http://beamalarm.com/Documents/dash_inverter_diagram.html) the inverter is located behind the foot panel on the drive side, it is black and about 2inchx4inch,disconnect the power leads and check your gauges again.
Start with the dash/gauge ground issue-- changing readings with different loads is a classic symptom.
Thanks to everyone for the information, I am here at Nacogdochess and I think I will let the Mfg. check all of the information you'all have given me. Thanks....
I have the exact same problem on my coach. I'm also at FOT awaiting for service on Monday. My Motorcade # 16144. Sure would like to know how they will fix that one.