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2000 Blazer high oil pressure gauge reading and voltmeter charge

Auto facts: 2000 Blazer

Mileage: 180,000 Engine: V6, 4.3 Liter Transmission: Automatic Drivetrain: 4WD

Oil pressure gauge readings have been around 60-70 psi (high) sometimes. This has been going on for about 6 mo. When I start the truck it jumps high, then tends to go down to normal (around 50-55 psi) as I drive 2-10 mi. Does not always return to normal.

The oil and filter are changed like its a religion every 3000-4500 mi. since 2001 when I bought the vehicle.

Do you think it could be the oil pressure sensor or sending unit?

Also, the Voltmeter is often (70%) not in the “neutral” position ( This too has been going on for about 6 mo.). It most often reads one notch in the negative charge. Less often it will pop one notch over neutral. If it starts in negative it usually stays in neg.

Battery is from 9/08, Alternator from 2/08, V-belt from 3/07.

I have a 2000 Blazer 4wd with 114k miles

Oil pressure is 60 psi cold. After the engine warms up, oil pressure is 20 psi at idle and 40 psi driving. Have a mechanic check the pressure with an external oil pressure gauge to rule out a defective sending unit or dash gauge.

The tight engine compartment and heat possibly cause a shortened battery life in the Blazer. The original battery was replaced at 2.5 years. The second battery (AC Delco also) lasted 3.5 years. I used foil tape (used for HVAC ducting) to repair the insulating blanket. The third battery is fine at the 4 year mark. Rather than depending on the dash Voltmeter, invest in a Digital multimeter. Harbor Freight has inexpensive ones.

The voltage at the battery terminals should be between 11.9V (fully discharged) and 12.6V (fully charged). A reading of 11V or less indicates a dead cell and the battery has to be replaced. With the engine running the voltage should be between 13.5 and 14.5V.

Also check the battery cables. Peel back the red cover on the pos. cable to clean off any corrosion. The pos. cable on my Blazer has to be cleaned on a regular basis.

Ed B.

Sounds like something funky with the instrument cluster causing both gauges to be flaky. When the voltmeter on the dash is reading low, put a meter across the battery. If it agrees, you have an electrical problem. If it reads normal—probably 14.5V–you have an instrument cluster problem.