fooisdone

I have a big electrical problem and I am not to good at finding electrical problems . So any help will be greatly appreciated.

Last night I was puling up to a stop when every thing excepted the engine and head lights (which were very dimm) died. About a half a second later the dash lights came on very dimm and the temp and oil pressure gauges were freaking out, going back and forth very fast. One I got stoped every thing went back to normal. I came to another stop and took off again with no problems.

After traveling 30 min at 65 MPH I got to another stop, every thing died again. I pulled off to the side of the road and checked everthing I could. No wires were hot, I could not find any smoke. I had been parked for 5 mins. and the lights and guages are still acting up. After waching the guages for a minute i Figure out that when the dash lights are dimm the tail lights are dimm and at the same time the temp guages are freaking out. When most the lights were dead ( the head lights were very dimm) the temp and oil pressure guage were pegged.

I figured that I limp it home with dimm head lights and a flash light to check the mechanical gauges. Once I started to move every thing started to work better by the time I got to the freeway every thing started to work right. They keeped working even after I got off the freeway till I slowed down to make a turn when every thing went back.

When I got home I checked the cables again still nothing. While I was doing that I noticed that acid was bubbleing out. I had a freind kill it but it woulden't die until he let off the break.

Today: I checked all the grounds and connectors I could, even the bulkhead adapter, could not find any corrosion or arking. The temp guage acts like a ammeter, when the head lights are on it goes past 3/4. The oil pressure gauge reads no pressure while the key is on. When you turn the engine on the pressure slowly peggs out.

Anybody got some ideas?
thank you in advance.

PS: I have to go out of town this weekend can I drive it like this or do I need to arrange a ride?

fooisdone

Sorry
Some how I posted this toppic twice...
Here is the link to the other one

Electrical Issues

imabnormal

mine did the exact same thing about a week ago. the battery had slid forward and the +terminal was touching the battery clamp. a short in the the always hot (at the alternator, starter primary, battery, etc) will do that. the battery boiling indicates a HUGE amperage draw. the battery itself could have shorted internally, but that sould make it not re-start. and maybe go kaboom in your face

ChrisLib

Did you feel the wiring for the heater grids? I have heard of the relays for them sticking from time to time. Sounds like something is drawing big amps.

fooisdone

My heater grids are disconected.

fooisdone

Ok, this is starting to make me mad.
Today I had time to take another look at my truck, everything was working like it should.

I'll make a post the next time it happens.

spunbearing

start checking ground wires

JimmieD

Sorry, didn't see this thread earlier in the week. Sounds to me like you might want to check the alternator's output. Seems like the problem only comes up at low engine speeds, like when alternator output is lowest. Also it apparently does this only when it's warmed up: heat is electricity's biggest enemy. After shutdown and cool off it's okay. That might indicate that the diode packs in the alternator are taking a vacation from time to time. Also whatever computer is used on your 1990 depends on an accurate refence voltage for all functions, and low alternator/battery output throws the whole system out of whack.

JimmieD

Trebor

Sounds like the regulator is loosing its ground. Try running a wire from the regulator mounting screw to the engine block. I never ran into an intermittent diode. They always checked out as either good or open when I used to rebuild alternators.

fooisdone

Well everything is back to normal, except for the head light witch don't work.
I took the alternator to autozone and thay told me it was good.
Then I took off the regulator, cleaned it and the fire wall.
Still no headlights. So I ran a temp switch it to the cab.
I'll try to more acuretly note the conditions if it happens again.

Thank you everyone for all your help.

fooisdone

Update:
Now that the head lights are ran off of a switch they are at least twice as bright!
Also since I cleaned the regulator the dash lights don't flash between bright and dimm at a idle!
The lights and gauges problem has not happen since the headlights went out.
What this tells me is the short was in the headlight circuit.

What do you guys think the best plan of attack is?
1) Find a good schematic and test the dimmer switch, if it is good tear apart the dash then start tracing wires.
2) Sack up and run 2 relays with a SPDT toggle or rocker switch.

PS: It was not the light switch that went out. (Repalced it nothing changed)

Trebor

Do you know the history of your truck? Has it ever been involved in a flood or submerged in water? You need to check all of your under hood plug type connections for corrosion from moisture. Also check the main plug that goes to the firewall on the drivers side. Remove any greenish corrosion and apply an electrical contact grease on the connections.