recently, my 99PSD (7.3, 2WD, 165K miles, TS 6 position switch always on the stock setting, Donaldson air filter conversion, straight 3.5" exhaust, ZF 6 speed manual) has developed a quirk. First, I think there is a possibility that I have at least one soft battery, although they are less than 3 years old and good 850CCA Bosch batts. Very short cranking times before it runs down when cold and the block heater is not plugged in, plus the voltmeter shows quite low while the GPR is working. At times it can visibly be seen to drop. However, even when plugged in, and starting well, and the voltage gauge is up where it should be, I have dim headlights for a few minutes/miles, then all of a sudden they will brighten to normal. the alternator looks to be a replacement unit, although I cannot be certain of the age. I'm wondering if I may have A) an alternator issue, B) possible the intake heater comes on and then when it quits, the lights come back, or C) some other problem within a control system. The battery terminals are clean, the GPR seems to work, although in our WNY single digit temps, I have cycled it twice which seems to get things started better. Thoughts? I'd like to get ahead of any issues before they get serious.

 

I would start by giving your battery terminals and connectors a thorough cleaning, they tend to corrode on the inside where you can't see it.

the dim lights after startup are normal, your glow plugs will run for up to about 2 minutes on a cold start, when they go off, your lights brighten up. i believe they are pulling some where around 40 amps.

Once the truck is warmed up, you can put a volt meter to the alternator, it should be reading just north of 14 volts.

 

Best 8 bux I ever spent. They had a special on and got two delivered for about 8 bux. This little thing tells you exactly what is going on. Whether glow plugs are taking power and how much, when they go off and what your alternator is doing.
12V-24V Digital LED Display Volt Meter Auto Car Cigarette Lighter Voltage Gauge | eBay

 

Mark, Just ordered two. One for the ole girl and one for the new to us 08. Great lead!!! 9 bucks for both free shipping.


(Still want to crab that Skyhawk btw)

Denny