Instrument Cluster malfunction.

[Tomm1468]

Hey all, I've been putting up with this for a while, but am starting to get tired of it. Ever since I moved the ground wire from c216 to c214 to get my V8 swap to read correctly, I've been having issues with my instrument cluster. all the dash lights are new, so i know they function, but when i turn the lights on, half will not light up, sometimes, other times they are all fine. They tend to flicker, and when I roll down windows, or turn on my blinkers the lights "blink" with it. and my oil pressure gauge moves up and down slightly wit the blinking. My temp gauge hasnt worked since the swap too, and I've noticed that my gas level indicator shifts around an 8th of a tank. Lots of problems all coinciding with my v8 swap, but also could be becuase my truck sat for a year, and being in PNW it was heavily rained on, and at one point had a serious water leak on the back window, so everything got all mucked up. I'm thhinking its not my alternator, I have a digital voltage gauge that reads around the 14.5 mark normally and about 13.9 when its cold out, but idk anymore. I figured i'd have to just get another cluster, since I've gone back in and looked to see if i accidentally messed the wiring up on it, but I dont see anything. any ideas before i have to drop 150$ on a cluster would be appreciated, thx.

 

[RonD]

The 6 back lights have 2 different 12v connections, so 3 bulbs on each 12v pin
But they share the same ground wire, pin 7 on the 12 pin connector
2000 Cluster wiring Diagram below

Assuming you are using the 2000 Ranger cluster

Tachometer wiring for 1996 thru 2003 Ranger clusters
There are 2 ground wires for the Tach, only 1 is used or neither
Only Pin 16 of the 16-pin grounded ==> V8
Only Pin 8 of the 10-pin grounded ==> V6
Neither grounded ==> 4cyl
So you have to remove pin 8 ground, not just "add" a ground to pin 16

That's just a refresher, lol

Check the main cab ground strap, rear of driver's side head(on V6), usually goes to wiper motor mounting bolt or its own firewall bolt with computer grounds
Add one if unsure, you can NEVER have 1 too many grounds

Ground wires carry the same amps as 12v wires, so if a device needs 3 amps, then ground wire flows 3 amps same as 12v wire flows 3amps
If either wire has an issue with the 3amps then flickering

If you only notice the flicker at idle or its more pronounced then could be a failed field coil in alternator
Warmed up engine leave it idling don't test after restart
Turn on blower/fan to high, head lights on
Test battery voltage
13.6 to 13.9volts is expected
Raise RPMs to 1,500 or so and hold steady, voltage should go up but then come back down to what it was at idle
If it was under 13.6v with fan on high and headlights on then alternator does have 1 bad field coil, it has 3 field coils
This is not a big deal and fairly normal for older alternators, i.e. dimming headlights at idle, battery is still staying charged when driving
If a 2nd field fails then battery won't charge much so becomes a big deal

 

[Tomm1468]

Thanks for the info, I went and made sure everything is in order, which it seemed to be, but I’ve started getting lower and lower voltage, I got to the point of running around 13.2v at night while driving with the air off. I decided to put in a new alternator to see what happens, and it changed nothing. Except now my mpg seems to have tanked, from about 17 city, I’m struggling to get 10 while driving super conservatively. I’ve also noticed that it seems to run rough and rich at random times. I’ll start it up and immediately reek of gasoline and be blowing heavy amounts of white smoke out the tail pipe, so I’ll turn it off and back on it everything will be fine again, no gas smell, no discolored tail pipe smoke. I feel like this is all electrical, but I’m not sure what’s wrong. When I installed the 5.0 I carefully went over both the rangers battery harness and the engine harness and inspected/ rewrapped all the wires. The only thing that pops into my head is that I have a battery that is a lot smaller than the explorer was meant to have. It has the cold crank power that I need but it’s significantly smaller than it should be. But idk. The problem seems to be slowly getting worse, so imma have to nip this in the bud before I get stranded somewhere…

 

[bobbywalter]

Thanks for the info, I went and made sure everything is in order, which it seemed to be, but I’ve started getting lower and lower voltage, I got to the point of running around 13.2v at night while driving with the air off. I decided to put in a new alternator to see what happens, and it changed nothing. Except now my mpg seems to have tanked, from about 17 city, I’m struggling to get 10 while driving super conservatively. I’ve also noticed that it seems to run rough and rich at random times. I’ll start it up and immediately reek of gasoline and be blowing heavy amounts of white smoke out the tail pipe, so I’ll turn it off and back on it everything will be fine again, no gas smell, no discolored tail pipe smoke. I feel like this is all electrical, but I’m not sure what’s wrong. When I installed the 5.0 I carefully went over both the rangers battery harness and the engine harness and inspected/ rewrapped all the wires. The only thing that pops into my head is that I have a battery that is a lot smaller than the explorer was meant to have. It has the cold crank power that I need but it’s significantly smaller than it should be. But idk. The problem seems to be slowly getting worse, so imma have to nip this in the bud before I get stranded somewhere…

rework the grounds on the passenger kick panel side

 

[RonD]

Check your volt meter on another vehicle or even 9v battery

Battery is only used to start an engine, car batteries are max 12.9v brand new

Alternator's power all electrics once engine starts, should be minimum 13.5v and max 14.8volts
Just after startup battery voltage(alternator voltage really) should read above 14volts

Alternator systems are very easy to trouble shoot with volt meter
Key off
Test battery volts, remember it, lets say its 12.5volts
Alternator's metal case will be the ground you use on all tests

On the back of the alternator is a stud/nut terminal, this is "B+"
Test B+ voltage should be EXACTLY battery voltage, as above, 12.5v
If not then you have a bad/corroded wire/connection from B+ to Battery Positive
OR........a bad ground to engine, move Volt Meter's black ground probe to Battery Negative, if you now see EXACTLY battery volts then it IS a bad ground to engine, clean up that connection, and retest
If volts match, then next test

Unplug the 3 wire connector on alternator, this is for voltage regulator inside
Test it's Yellow wire, should be EXACTLY battery voltage, 12.5v
If not, bad/corroded wire/connection from Yellow wire to Battery Positive
If so next test

Test Light green/red stripe wire, should be 0 volts
Turn key on
It should now be almost Battery Volts, can be 0.2 less and thats OK
This is the ON/OFF switch for alternator, and Battery/Charge Light on dash
If not then fuse is blown in cab fuse box, which fuse varied by year of course, in 2000 its fuse #15

If these 3 wires test as OK then truck side of charging system is OK
Plug back in the 3 wire connector
There is a white jumper wire on 3 wire connector, make sure it is plugged in to its single spade terminal on alternator, unplug it and plug it back in to clean connection

Start engine
Test battery voltage, higher than 14volts is expected
If under Battery voltage then alternator is DEAD
If under 14volts then voltage regulator in the alternator is bad, or 1 or 2 of the fields in alternator are bad

New 3rd party alternators are a roll of the dice now-a-days, some have had to exchange them 2 or 3 times to get a working one

Auto parts stores can NOT test alternators, YOU CAN, and you just did with above tests

 

[Tomm1468]

All righty. So i started my charging system testing, but first i figured I would once again check all my grounding points in my truck. I have had trouble with the grounding in the past.
Well, it (so far) seems to be that I forgot to bolt down my spark coil rack to the engine. I have one of the upper intake bolts that holds it on usually, and don't care about the other two. It seems that I forgot to bolt that one bolt down last time I took it off a few months ago (around when the ticking of my gauge cluster started). So I bolted it back on, now my truck is once again reading 14.5 regular, and about 13.9 - 14 when fans on high and lights are on and my oil pressure switch no longer moves up and down with my turn signals.

Granted, this is after running the truck 2 or three times for just a few minutes each, so I will be keeping an eye on it for the next little while.
I was really hoping that fixing this would fix my coolant gauge not reading (actually moves down from neutral to as low as it can go when I start the car), alas it did not. so I'll still just have to keep tracking my engine temp through my OBDII live stats, lol.
thanks for all the help, I am really hoping my MPG goes back to the 17ish I was getting a little while back.

 

[RonD]

Coolant temp sender is a Ground path for the temp gauge via engine block

Sender will have a Red/white wire or if older a Black/blue wire on the sender
The sender's threads are the ground, so it must have bare metal contact with intake/block, if you add sealing tape leave bare threads at the bottom

Test
Remove the wire from the sender
GROUND that wire to battery negative
Turn on the key
Temp gauge should go to HOT, all the way up

If so then wire and gauge are OK, replace sender, or make sure its grounded

If gauge doesn't go to HOT then its a wire or gauge issue


Later model temp senders will have 2 wire connections instead of just 1
These require a ground wire as well as the red/white wire
These were made/used when engines started to get more external plastic parts so no reliable ground from the block
These, of course, could not be used with 1 wire system unless you added another wire
Temp senders are 12volt
ECT sensors are 5volt
So they are not the same thing even though they look similar

 

[Tomm1468]

Coolant temp sender is a Ground path for the temp gauge via engine block

Sender will have a Red/white wire or if older a Black/blue wire on the sender
The sender's threads are the ground, so it must have bare metal contact with intake/block, if you add sealing tape leave bare threads at the bottom

Test
Remove the wire from the sender
GROUND that wire to battery negative
Turn on the key
Temp gauge should go to HOT, all the way up

If so then wire and gauge are OK, replace sender, or make sure its grounded

If gauge doesn't go to HOT then its a wire or gauge issue


Later model temp senders will have 2 wire connections instead of just 1
These require a ground wire as well as the red/white wire
These were made/used when engines started to get more external plastic parts so no reliable ground from the block
These, of course, could not be used with 1 wire system unless you added another wire
Temp senders are 12volt
ECT sensors are 5volt
So they are not the same thing even though they look similar

That worked so well. I grounded it and the gauge shot up to all the way hot, so I'm thinking its one of two things, possibly both.
1. I got a new sensor (pretty sure its motorcraft) when i rebuilt the engine, so theres a possibility that it just doesnt work.
2. i painted my engine when I rebuilt it, if the paint seeped into the intakes coolant temp sensor holes, that would keep it from grounding properly.
im going to go get a new sensor.

This is great news, though it does throw a wrench in my idea that my insturment cluster is bad. the only things left that are weird are.
one background light doesn't work..
and my fuel gauge ocassionally moves around (about an 8th of a tank) .

i appreciate the help!!!