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Old 04-27-2019, 07:35 PM   #1
sawman
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More problems,1990 1500 v6 wiring problems,

1990 1500 v6,wiring problems,purchased this pickup with problems,with forum help got it to keep running,now that it runs heres the things that dont work,no dash lights,radio doesnt come on,no turn signals,no gauges work fuel, temp ect,the high beam light stays on with lights not on also both turn signal lights are on,but dont work,engine light works comes on and then gos off once it starts,what did i get myself into,lol,and yes the trucks color is county yellow,any help,thanks
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Old 04-29-2019, 05:20 PM   #2
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Re: More problems,1990 1500 v6 wiring problems,

Update-- check all fuses,they are good,have power to fuse box,no oil,volts or fuel,tach,speedo gauge ,they dont move,with key off if i push cigar lighter in,which doesnt work the temp gauge moves all the way over,and the turn signal lights light up and a buzzing comes on under dash ??? now what
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Old 04-30-2019, 05:10 PM   #3
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Re: More problems,1990 1500 v6 wiring problems,

I going to take a wild stab and say there has been some hacking of the dash wiring. I would look at it or pull out gauges and all to check all the connections.
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Old 04-30-2019, 05:21 PM   #4
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Re: More problems,1990 1500 v6 wiring problems,

Update-- if i turn power to heater off were just the screen says off the gauges work fine,turn the heater power on gauges act up,oil temp,volts and fuel work,no tach speedo or wipers ,aarrr.
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Old 04-30-2019, 10:49 PM   #5
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Re: More problems,1990 1500 v6 wiring problems,

That maybe a grounding issue. You may need to make your own good ground circuit for the dash area. Also Make sure you have good ground straps from the cab to frame and frame to engine, and the bed area also. Weird frreaky stuff like that many time can be related to bad or lacking grounds.
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Old 05-05-2019, 01:30 AM   #6
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Re: More problems,1990 1500 v6 wiring problems,

i made a you tube video of the dash gauges acting up, so the problem can be seen,dont no if i put it here right.
https://www.youtube.com/watch?v=p9oh57P8LBM&t=10s
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Old 05-17-2019, 11:49 PM   #7
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Re: More problems,1990 1500 v6 wiring problems,

update,,,i cleaned all gauges/connection will be putting back in this weekend didnt see or find anything wrong,Question is there suppose to be a ground wire on the gauge cluster ? or is it in the wire harness,i found down at the bottom of dash 2 ground wires bolted in,was think running wire from them to the frame ,also more problems turn on the inside dome light and all gauges stop working and a dash light lights up saying check gauges,and the dem roller switch next to the headlight switch that dems the dash lights also moves the gauges rrrrrrrrrrrrrrrrrrrrrrrrrrr
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Old 05-18-2019, 06:16 AM   #8
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Re: More problems,1990 1500 v6 wiring problems,

I believe the ground is in the harness, but you can always add another if you are not certain,
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Old 05-18-2019, 02:37 PM   #9
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Re: More problems,1990 1500 v6 wiring problems,

theres a cover below the column under it 2 wires come out of the dash harness and are attached to the metal dash brace only other ground i found is under the hood top of motor harness has 2 wires going to the thermostat bolt ,i think that is a silly place for a ground .
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Old 05-18-2019, 05:34 PM   #10
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Re: More problems,1990 1500 v6 wiring problems,

tried grounding it better, didnt help.if i keep the heater off gauges work somewhat,so i unpluged the plug of the back of the heater control,everything works turn on lights,gauges work fine,dimmer switch works fine,all gauges work,still no tach or speed gauge,i see on the back of the heater/ac control tag says reman so i no its been changed,took it apart to the eye nothing wrong,took the control faceplate off seen this burn mark maybe from light or ?
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Old 05-19-2019, 08:40 PM   #11
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Re: More problems,1990 1500 v6 wiring problems,

That's normal on working Vacuflourescent Displays.
On radio tubes it's called a Getter spot.
You need to worry about the VFD if you see white spots not black.

https://electronics.stackexchange.co...r-a-vfds-glass

If you aren't experienced in this kind of repair with the right tooling I'd farm it out.
You can quickly damage it beyond repair.
The PC boards are usually thin and the pads lift off the boards very easily in inexperienced hands.

There's one 30 year old Electrolytic capacitor and a TO220 package device with a large heatsink that's probably a linear voltage regulator... LM7805 or something similar. There may be a zener or power diode as well. Those are the places I'd look first for failures.
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1969 Dodge Polara 500 B383, A833 SOLD
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1976 Chevy K20, 6.5L, NV4500/NP208 SOLD
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2000 GMC C2500, TD6.5L, NV4500
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Last edited by hatzie; 05-19-2019 at 08:55 PM.
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Old 05-19-2019, 10:35 PM   #12
sawman
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Re: More problems,1990 1500 v6 wiring problems,

Quote:
Originally Posted by hatzie View Post
That's normal on working Vacuflourescent Displays.
On radio tubes it's called a Getter spot.
You need to worry about the VFD if you see white spots not black.

https://electronics.stackexchange.co...r-a-vfds-glass

If you aren't experienced in this kind of repair with the right tooling I'd farm it out.
You can quickly damage it beyond repair.
The PC boards are usually thin and the pads lift off the boards very easily in inexperienced hands.

There's one 30 year old Electrolytic capacitor and a TO220 package device with a large heatsink that's probably a linear voltage regulator... LM7805 or something similar. There may be a zener or power diode as well. Those are the places I'd look first for failures.
So do you think this is were my problem is ? also do you no were i can get one of these, thanks
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Old Yesterday, 08:06 AM   #13
hatzie
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Re: More problems,1990 1500 v6 wiring problems,

Quote:
Originally Posted by sawman View Post
So do you think this is were my problem is ? also do you know were i can get one of these? thanks
It might or might not be where the problem is. The first thing I always check is electrolytic caps, voltage regulation, and power diodes. Then look I for thermal damage, cold solder joints, and errant pieces of metal and crud making non-factory connections under the microscope.

If you don't know where to get capacitors, voltage regulators, resistors and diodes you don't have the experience to not damage the board. This is not a common part. If you damage it from inexperience you'll have difficulty replacing it.
The HVAC controllers have microchips that are fairly static sensitive and made of unobtainium. Care needs to be taken to not burn em up from errant static electricity.
This board is not one to cut your teeth on. My advice is to farm out the repair. If you make a mess, that a tech can actually repair, it'll cost double or triple what it would if you hadn't screwed it up.

When I get boards with lifted pads and other physical damage I contact the owner to let them know that the price just went way way way up. If the board turns out to be un-repairable because the static sensitive parts were damaged or there's internal damage in a multi-layer board I still charge for my diagnostic time to reach that determination. That may sound a little harsh but I charge for my time.
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1959 M35A2 LDT465-1D SOLD
1967 Dodge W200 B383, NP420/NP201 SOLD
1969 Dodge Polara 500 B383, A833 SOLD
1972 Ford F250 FE390, NP435/NP205 SOLD
1976 Chevy K20, 6.5L, NV4500/NP208 SOLD
1986 M1008 CUCV SOLD
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
2009 Impala SS LS4 V8


RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...Please include at least the year and model in your threads. It'll be easier to answer your questions.
And please let us know if and how your repairs were successful.

Last edited by hatzie; Yesterday at 08:33 AM.
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