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Ask 32dmadden Your Own Question
32dmadden, Auto Repair Shop Owner
Category: Dodge
Satisfied Customers: 1207
Experience:  A.S.E. Certified Master Technician, L-1 37 yrs. Auto Repair Experience
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98 Dodge Ram Van 2500, check gauges fault (no DTC code).

Customer Question

'98 Dodge Ram Van 2500, "check gauges fault" (no DTC code). Oil pressure gauge forced/falls from 1/4 full scale to zero by the controller (computer) at any idle after warm up. Test oil pressure with mechanical test gauge (has 12 psi reading). Replaced oil pressure sensor; yet no success?
5.2 L engine (may/must have been replaced by previous owner). When the controller releases the gauge (at above idle RPM .. i.e. slow acceleration from a stop light) needle jumps back to 1/4 full scale... How to DIY the fix?

Please, may I withdraw my question?
Submitted: 6 years ago.
Category: Dodge
Expert:  32dmadden replied 6 years ago.
There could be a communication error on the bus line. If this occurs the computer will hold the gauge at its last reading for 12 seconds, if there isn't any message received after 12 seconds the gauge will fall to the lower end of the scale. But since it seems to come to life above idle that it is getting some communication. Check the oil pressure sensor wires with sensor unplugged for a short to ground or power. On the gray and black wire check for a short to ground. The orange wire will have 5 volts with the key on. If all checks out then it may need the computer reprogramed. Of course a qualified tech will have to do that. There is also a micro control module in the instrument cluster where the info that has arrived from the computer is directed to the correct gauge. BotXXXXX XXXXXne is if you don't have several thousand dollars worth of special equipment it is hard to find the problem. For about one to two hours of trouble shooting time you will be ahead. When you see the price of the modules and computers you will see you need to know what is wrong before you start replacing parts. I'll be here if you need more help.
Customer: replied 6 years ago.
the oil sensor is just a two wire part - no orange wire. By plugging on a variable resistor instead of the sensor, I can make the gauge move full scale to below about 1/4 scale - then the system presents a "gauge check fault", if I return to 1/4 scale the fault clears.
The parts books call for Airtex # XXXXX (sensor OFF at 0..10 PSI), but since 6 psi is good lower limit of pressure the "right" part should be 1S6622.... Can I withdraw my question please?