2000 Ford Ranger 5spd with 3.0 v6

I have a 2000 Ford Ranger, 5spd with 3.0 v6. The speedometer will jump around or quit about half the time whenever you push the brake pedal or use the turn signals. I’ve cleaned all the grounds I can find including taking the battery cables off the clamps and cleaning them, and I had to clean all the fuses (inside box and outside box) because most of them were corroded. This helped a little bit, but it still does it. Occasionally, I’ll hear a buzzing/crackling noise like electricity arcing when I use the brakes or the turn signals which sounds like it’s coming from the left side of the dashboard. I took off panels and the fuse box, but I don’t see any sign of arcing. Also, the noise only occurs when the truck is actually moving, never when it’s sitting still. Also, the engine has a slight flutter at an idle. I hooked up a computer, and the O2 sensors were erratically jumping between rich and lean, so I replaced all of them. It says Insufficient EGR flow detected, so I did put a new EGR valve on and cleared the codes, but it still reads the same. And lastly, the computer refuses to finish either of its diagnostic tests. I’ve tried the Koeo and the koer tests, and neither will complete.

Please help! I’m at a loss, and I don’t have the money to take it to a mechanic.


It sounds – just like you are implying – there’s a corroded (high resistance) connection somewhere. I’d focus on the interaction of the brakes and the speedometer probably. You need to find where in the schematic the stabilized voltage is produced for the speedometer reference voltage. I’m expecting that is changing when you step on the brakes. The brake lights must be using current and causing a voltage drop across a high resistance connection, which is affecting the voltage reference for the speedo.

If you don’t have access to schematics or don’t have experience/tools for electrical testing, one thing you could try is to visually identify and clean all corroded connectors/fuses that seem to be associated with the tail and brake lights.


If you are uncertain about the battery and alternator condition, having the battery and charging system tested would be the first order of business.


“O2 sensors were erraticcally jumping between rich and lean”

The FRONT sensors are supposed to be doing this

“insufficient EGR flow detected” . . . check for rotten vacuum hoses at the DPFE sensor