I have another post about MY disco. I stumped there. Gave up for a bit and I've been driving my wife's D2 for the time being. It's been having all sorts of issues now also & fixing it has become a priority in order to get me to/ from work reliably again. I need some help with the divide and conquer process. Also, if anyone in the South Jersey area has a recommendation for a good indie shop, I'll be grateful.

Problem #1 symptoms:
Slow/ No start - Starter would turn real slow a time or two and either start after a strained slow crank, or the battery would die.
What I've done:
Replaced Battery (was a quick first step since I had a free replacement)
Hooked up an Ultra-Guage to check voltage.
I re-ran a clean chassis ground (couldn't get a consistent resistance when metered & thought it was suspect)
Replaced starter. Cranks good now. My assumption is the bad ground killed my starter while I was fiddling with the battery. - This problem may be resolved.

Problem #2:
Voltage is low. Initial voltage (read from Ultra-Gauge) reads normal (13.5 - 14.1) at start up. After driving a few miles or when put under load (AC on, lights on, etc) it drops down into the 12.0-12.5 range. Early into the drive, turning the AC back off will bring the voltage up some (into 13.0 to 13.2 area). After the truck has run for a bit though, removing the load, increasing the RPMs don't seem to make much of a difference. he voltage will just drop down and hover down around 12v.
What I've done:
Swapped in a known good alternator from my D2 (rebuilt locally about a year ago & had given me good output since)
Went to a big box auto parts place & had them check the charging/ starting system. Their reading basically came back 0. He said that the alternator wasn't showing up at all in his test as being connected.

Problem #3
Truck dies while driving and will not restart while hot or will restart only to die again 30 seconds or so later. Truck will run and drive fine once it has cooled down. This has happened twice. Once while driving, once while idling in the driveway for an extended period. A pending code P0340 (Camshaft Position Sensor Circuit Malfunction) was present both times this happened.
What I've done: Nothing done for this yet. Symptoms sounds pretty typical for a bad crank sensor, but as this is recent, I haven't looked into it much. Not sure if a bad crank sensor can cause the P0340 code or if it is actually something to do with the camshaft sensor. I assume the two are related. I have a new crank sensor to install if you guys think that it could be the problem.

So the big question, do you think I have one underlying problem? Bad ground maybe that screwed things up all over the place? Several unrelated problems that just popped up as a coincidence?

Where would you start? I need help getting back on the road.

 

I inserted my comments above. Don't mind the all caps, I'm not actually yelling...

 

No worries about the caps. I use AutoCAD and type in caps a lot on another screen I inadvertently leave them on and "yell" in quick emails all the time.

-Voltage is normal (13.6 - 14.2ish) while cranking. and it drops very slowly from there and drops significantly when a load is added like the AC, or headlights. The alternator from my other D2 that I swapped into it was good & read about 14v +/- 0.2 with normal operation when in my vehicle. Loads like the lights & AC didn't seem to have much impact if any when it was in my D2 prior. Only thing I can come up with is maybe the bad ground that I originally overlooked could have screwed up the voltage regulator originally AND in the one I swapped in?

-Battery was replaced early on with the troubles & the replacement has tested good.

-From what I have read camshaft sensors rarely fail. I can check the wiring. I am not sure how to test the sensor itself.

 

It's normal for voltage to drop momentarily to 10V while the starter is engaged and most of the time it's just a for a couple of seconds. 13.6-14.2 is actually quite higher than what id expect. If you have one, I'd do my trouble shooting with an actual digital multimeter vice the gauge you mentioned.

Well, you can't go with 'rarely fail'. The fact is that you a) have the code, and b) they do actually fail. I don't have it in front of me but you can probably do a search on how to test them. Oh, you'll need a multimeter for that.

They all basically work the same and I have a Volvo that a while back was exhibiting similar symptoms but wasn't even giving a code - ended up being the cam position sensor. I always grab a few sensors like that when I hit the Pick n Pull

 

Sorry. I mis-spoke earlier. 13.6-14.2 is the initial voltage AFTER cranking. WHILE cranking it's around 10-10.5.

Replacing the crankshaft sensor fixed my stalling/ not starting problem. Starts fine now w/ no codes. I took the alternators to my alternator guy (glad there are still a few guys left) assuming I had fried the voltage regulators and he said they both tested good! I got out my RAVE & meter and started tracing wiring for voltage drops etc. What I eventually found was the yellow wire at the ignition switch (which feeds through the battery light and then goes on to become the small brown/ yellow wire on the back of the alternator which tells the alt to kick out voltage) had a bad connection in the switch. When I tested it a couple of times at the alternator it had 12V, but several times while I was testing it would only measure 3-5V when the key was at position 2. Tapping the side of the ignition switch or adjusting the key would make it jump up to the needed 12+ volts. Sure enough, when it would have 3-5V out of the ignition switch the alternator wasn't generating. 5V was probably enough voltage to keep the battery light off, but half the time my alternator didn't have an input signal to generate voltage. No input = no output. I sprayed the switch/ cylinder out with contact cleaner and lubed it back up with WD40 & it consistently sends the 12V signal to the alternator now.

Only odd thing I noticed afterward was that I still had 0.5V on the yellow wire once the switch was off & the key was removed. I don't feel this is normal. Anyone familiar with this?

Nothing better than an intermittent electrical fault to complicate life sometimes!

I wanted to post an update for future head scratchers. Hope I help someone one day.