Hey y'all!
As I'm slowly working-through several issues on the new-to-me '99 Disco i, I'm finally getting to an electrical issue, which I'd like to resolve before proceeding any further on other electrical issues, because I'm not convinced I can accurately trouble-shoot the rest as long as this is going on.

Help me, please?

in the mornings on my way to work, i've noticed the headlights (and dash-illumination) "pulse". The pulse does NOT go away when revving the motor, but it 'looks' like that kind of pulse. When cruising at 65 mph, voltage to my UG measures between 14,08 - 14.96, and is constantly fluctuating, even though electrical-load and engine-speed are constant. (at least in the sense that I'm not purposely changing either). And by "constantly", I mean that it changes readings every 2 seconds when the UG samples/ updates.

I cannot help but think this -could- be related to my VSS problems, and possibly even my sometimes-bad-sometimes-good '02 sensors. ??

Or maybe they all do this?

waddy'all know?

 

Well it looks like we ruled out voltage regulator. It could be a loose connection somewhere. I don't think any obd2 sensors would cause lights to do that.

Does it do it when the truck is at a stand still? Or driving? Has this been happening since you bought? Have you done anything with wiring on the truck?

I don't think it's a short. If it where you would see it on your ug. It has to be a loose connection somewhere in the truck. Try taking electric clean and start one by one pulling major connections apart cleaning and putting them back together. Look for burnt connection while doing this. Also loose wires at the connection. Also check your fuse box for any bad connections there. That's going to be a tough one to find.

 

And don't forget the ground bond conections that link battery (-) to the frame, and engine block to chassis. If it does it at idle, you can attach (-) battery post to chassis with a battery jumper cable.

 

How did you get your UG to show you battery voltage?

 

good question, and BTW, I think 14.96 is too high, that regulator is not doing what it needs to do.

 

Wow guys! thanks for all the responses!
I'll try to answer all of the questions you've posed.

yes, it does it at idle, at standstill, at speed, with no perceived difference in attenuation or modulation.
Yes, it has done it since I bought it, 10 days ago.
The UG will show "UG Voltage", which is simply system voltage being fed to the UG, just as if you were testing at the cig-lighter, or fuse-panel.

I've uploaded a couple of videos I took this evening. See below. you'll note voltage in the upper left of the UG. if you look closely, you can see the "pulses" in the lights and dash illumination, about 4 times/second-ish.

And this evening, I saw it go past 15.00 volts twice, and dip under 14.00 volts as well. (15.09-13.95)
So how would I isolate the voltage regulator, to test if that's it? And best place to buy a replacement?
AND: since the O2 sensors and the VSS are all based on the voltage going to ground, is it possible that this is variance is playing hob with my sensors?

 

The voltage regulator is part of the alternator, it's possible to replace it but I never bother. I either buy a new one or have it rebuilt (depends on what I'm working on). Voltage over 15 will definitely make things act weird. (As well as boil your battery relatively quickly)

 

An alternator should never charge over 14.7v. So think its your alternator/regulator. Take it in to any auto parts store and have it tested. i don't want you to **** money down the drain to just buy a new one.

 

Under normal charging, voltage typically runs 13.6.

As Gale said, much longer at that voltage and an acid battery will boil over. BTDT.

I'm with everyone else - pull the alternator and have it tested.

 

Here's pix of regulator (black thing in dead center, with white part on back of it), you can dismantle alternator and replace it. Also see great rebuild article the pix came from https://landroverforums.com/forum/di...ght=alternator

Lots of sources for regulator/brush sets, one is http://www.iat-usa.com/Regulators.pdf