A battery light appeared on my dash. A new DIYer, I started doing what you are not supposed to do and threw parts at it. I didn't mind as I was learning as I was doing it. The truck has a new battery, ground connection checked, replaced the alternator, but still light would not go out. I saw the tensioner pulley "walk" back and forth and thought the pulley or belts were the issue, so I replaced those. I then realized the power steering was not working properly and checked the pump and sure enough, it appeared that the pwr steering pulley was getting "stuck" at a certain spot each rotation. After a bear of a time replacing the power steering pump and thinking I solved the problem, I am still seeing the battery light and when I look in the engine, the tensioner pulley still appears to "walk" back and forth. Any thoughts on next steps would be appreciated.

 

What is the sitting voltage (truck off for a while) and running voltage?

 

Sitting voltage is 12.31. Truck had been sitting for 2 weeks. When I start it up the voltage fluctuates (which seems to mirror the pulley moving back and forth) from 13.54 then momentarily drop to 12.75 then back up again to 13.54. Its a fairly consistent fluctuation back and forth.

Checked the codes and am getting PO622 Generator Field/F terminal circuit

 

At face value that looks like a faltering alternator. It should not fluctuate so much. Generally after cold start, the voltage will remain high as engine temps come up then the voltage output will go down. 13.0 would be low and you are getting just 12.75. I know you replaced the alt, but if it was a rebuild/generic then there is a chance it was faulty out of box. Never assume new parts are perfect. I chased that rabbit hole once LONG ago with some new OEM spark coil packs. Turned out the new parts, which I ignored since they were new, were the issue all along.

 

Thanks. I was wondering if that was a possibility.

 

UPDATE: Replaced alternator with OEM alternator, but still no change. Took truck to shop (well respected foreign auto repairs) and they could not get scan tool to read all the fault codes. Told me needed Land Rover Dealer type scan tool to read it, but multiple fault codes and system malfunctioning to ground would indicate mouse has eaten some wires. Plausible in that there was evidence of mouse making a next in glove box before I took it into the shop.