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Repair Topics / Electrical
System-1 / Electrical
System-2
Car Electrical System Questions and Answers This
category contains featured questions as
examples. They relate to most vehicles.
Question: 1998 Ford Ranger_mileage: 103,000. When I step on the
brakes the right directionals light up solid with the brake lights. The
bulbs all seem to be intact. Is it a ground? Is it a Switch? If so
where?
Answer: You are apparently getting feedback from your brake
light circuit to the turn signal circuit. Verify that the taillight
bulbs are the correct one for your car. If your car is equipped with a
wiring harness for a trailer verify that it is not shorting out between
connections.
Question: 2002 Chevrolet
Silverado 6.0_mileage: 115,000. A few things are happening: The odometer
has gone back to zero, sometimes it will not come on when the truck is
started, and sometimes it reads error in the odometer read out. The
battery light also comes on some times and will not go off till I turn
the truck off and restart it. Also when the odometer does have mileage
on it and not error it will reset back to zero when the truck is turned
off.
Answer: It appears that you have a faulty instrument cluster.
Question:
2002 Chevy Trailblazer LT Vortec V6
4.2_mileage: 60,000. This problem is intermittent and I apparently
haven't noticed all of the affected components because I notice
something new each day! My 02 LT is fully loaded with 60k miles. A
few days ago, the keyless entry didn't work. Immediately I assumed the
battery and replaced it the next day. I hit the unlock button and it
still wasn't working so I thought maybe the whole keypad was dead. I
went home and tried the spare...It didn't work either. I didn't put much
thought into it until the next day on my way to work it drizzled rain
for a few miles. I turned the knob for my rear windshield wiper and
nothing happened. I pressed the button for fluid...still nothing.
I parked and turned off the engine after arriving at work and sat there
for a minute after realizing that my radio shut off when I turned the
key to off and I couldn't roll up my window. Under normal operating
conditions, my radio will play for 10 minutes, the windows will roll
up/down and the interior light will come on when the engine is OFF as
long as the door has not been opened. I was baffled. I went
into work and when I came back out for lunch... (4 hours later) I
pressed the keyless entry...It unlocked! Got into the truck, turned on
the rear wiper...It worked! Came back from lunch, turned off the
engine...radio kept playing! This has gone on for about 1 week
now. On/Off. I'm confused! Is it a relay? I have searched the internet
for HOURS looking for any kind of explanation...Chevy dealer said it
needs diagnostic and possible a new computer assembly switch. Please
help!!!! Thank you!!!
Answer:
Based on what you have told us, replacing the
Body Control Module should fix your problem.
Question:
2000
Ford Excursion 6.8L V10_mileage: 120,000. The
interior lights and running board lights now
stay on dimly during vehicle operation and for
25 minutes after vehicle is shut off or if you
open and then close a door with vehicle already
shut off. There is no Door Ajar light, no
Check Engine light and the one code in the
computer said pedal stop switch, which was
replaced. Problem remains. No
drivability problems. A big hazard for my
wife to drive at night with all the interior
lights on.
Answer:
The problem with the interior lights and
running lights is probably due to a faulty
generic electronic module (GEM).
Question:
1989 Jeep Cherokee 4.0_mileage: 200,000. My son
has a Jeep Cherokee that we have done a good
amount of work to. We are down to the last
problem and are stumped. The alternator is
putting out about 14 volts and the battery is
steady at 12 volts. The volt meter in the dash
reads at best 12 volts and whenever any light or
accessory is used it drops to below 9 volts. We
have used a volt meter to check everything and
we keep coming back to a short. If you connect a
voltmeter to between the negative post on the
battery and ground the other lead to the chassis
it read 0 volts. Turn any lights or accessory
like the rear defog and the volts go as high as
6 volts. This would indicate a short. Problem is
we can not find it. It has to be in a main line
because any item that uses power adds to the
short volts. Any help would be great
Answer:
The first thing we would check, based on the
circumstances that you have described, would be
the ground wires to see that they are in place
and making a good connection, especially the
ones to the body.
Question:
1999 Pontiac Grand Am 6 cyl. mileage:
75,000 The other day I
started the car and noticed the dash instruments
do not work: speedometer, tach, gas, temp... nor
does the power windows, or the heater fan.
I checked all of the fuses, and they are ok.
I cannot find anything that has all of those
functions in common, do you have any suggestions
as to what it could be?
Answer:
The common function you are looking for is the
body control module.
Question:
2002 Chevy Suburban 2500 mileage: 73,000. When
you step on the brake, the #1 fuse blows which
not only controls the brake lights but also the
flashers and buzzer. I spent 4 hours at the
Chevy Dealership yesterday. They checked the
wire connections from under the hood to the rear
of the vehicle. They replaced the brake switch
and the directional switch located in the
steering column with NO positive results. ANY
IDEAS WHAT THE PROBLEM MIGHT BE?
Answer:
Most Suburban's were equipped with an extra
wiring harness for connecting trailer lights.
Check out that harness as it may be causing your
problem.
Question: 2002 Honda Accord
mileage: 57,000. What conditions would short the
voltage regulator inside the alternator and at
the same time blow the headlights, interior
lights, dash clock and damage the radio? The
reason I ask is that after I got my car back
from the body shop from collision to right front
of vehicle (passenger side - battery side) they
claim the electrical problems I now have were
not a result of the accident since the battery
tray was not damaged? Does not sound right to
me. After further investigation the battery left
cell was either shorted or somewhere inside
there is a break thereby making it "open
circuit". Would the damage to the voltage
regulator have happened during the impact or
during the trip home after the accident?
Currently the alternator is punching out 18V. A
little insight here would be appreciated.
Answer: Electrical problems
are tough to troubleshoot. Check the wiring
harnesses for damage, especially the ground
wires. Also, have the battery load tested to be
sure there is not a shorted cell inside.
18-volts from the alternator is too high. This
may be due to a missing ground wire or a faulty
internal voltage regulator.
Question: 2001 Cadillac SLS.
I am writing you today because of a problem that
started directly after my car was picked up from
my mechanic last week. My car was in the shop
having the starter motor replaced, and I am sure
you know, that on my car you have to break down
most of the top of the engine to get to it -
what a pain that project can be. I picked up the
car and everything seemed all right with it,
until it became dark out. The background light
on my tachometer and speedometer were
flickering. I started looking at things more
carefully - I noticed that everything was
flickering: Headlights, interior lights, dash
board (not digital stuff though) and the best
part is a random clicking noise like the turn
signal noise is going off but a lot faster -
This happened over 1500 rpm. So I called my
mechanic, and explained to him what the trouble
was and he suggested tightening all of the
grounds and changing a blinker bulb that had
burned out. So I checked the grounds, and
changed the bulb. When I started the car after
that I had no back light for the Speedometer,
Stereo, Shifter, dimmer switch and the left side
running/tail lights for the back of the car do
not work, (But the brake lights do across the
entire back end and the Speedo also still works
with no lights). So my question is, since all of
these accessories are not on one circuit/fuse
line, do you think that the improper
installation of a Starter motor could cause
these symptoms? Do you have any Ideas of what
this could be?
Answer: It is possible that
an improper installation of the starter motor
did cause your problems. From what you have
described it sounds as if the body control
module is failing. The main power wires have to
be removed and reconnected when the starter is
replaced and if something were reconnected
improperly, it would short out the body control
module.
Question: 2002 VW Jetta
mileage: 34,000. I have a VW Jetta that I leased
in Sept 98. I am outside my bumper-to-bumper
warranty. I have been experiencing numerous
electrical problems over the last 2 mos....possibly
related I don't know. The rear power windows
only work sporadically.... when they decide not
to work.... there is no noise...they just don't
go down. A couple of times each week my coolant
indicator light comes on for a while then goes
off. My coolant level has not been low. There is
no change in the temperature gauge...and no
smoke/leaks/etc that would indicate any problem
w/the coolant level. My alarm activates itself
on occasion when I am driving. I know this
because I'll be driving and I see the red light
on the driver side door lock start blinking as
if the alarm is set...also the horn beeps just
as it does when you lock the doors from the
outside and activate the alarm. Furthermore,
when this happens I cannot unlock the power
locks unless I use my keyless entry key chain
(which doesn't work outside the car) inside the
car. That is the only way I can de-activate the
alarm and unlock the doors. I have had my
vehicle into 2 VW dealerships, paid for
diagnostics...and they tell me nothing is
wrong.... that the car is running to manufacture
specs. I have been corresponding w/VW customer
relations as well. So far, no answers. Any
suggestions?
Answer: Electrical problems
can be extremely frustrating. We suggest
checking the wiring looms for damage or loose
connections. Also check for poor ground
connections. You may have a faulty body control
module.
Question:
1999 VW Jetta Automatic mileage: 50,000.
My problem started when my electric sun
roof, dome light, and electric locks were not
working.
My clock was also not working right; it came on,
but did not keep the time.
It always goes back to 12:00 when I turn
the car off.
I checked the fuses; one was blown, so I
figured that was the problem.
I had not replaced the fuse yet, but when
I got in my car yesterday, my speedometer and
tachometer were not working.
I replaced the fuse (with the right size)
and my dome light came back on (it did nothing
for the speedometer) but when I attempted to
open my sunroof the light dimmed and the fuse
blew again.
Any ideas?
Are the two problems even related?
Answer:
It sounds as if both problems are
related. There
probably is a short in the sunroof motor and/or
the control switch for your sunroof.
Question:
2002 Toyota Camry miles: 78,900.
Last past two years, I have had problems
with the electrical locks, seatbelts and
windows.
I believe the problem my have originated in the
driver's side panel.
If I open the driver's side to fast, the
seatbelt will not go forward all the way.
The passenger side window does not go up
or down at all.
Now my car will not stayed locked.
If I lock it from the drivers side, when
I shut the door it will unlock.
If I lock it from the passengers side it
will stay locked, but not for long.
When I return to my car all the locks are
unlocked.
I do hear a clicking noise in the panel just
above the glove compartment when shutting doors.
Answer: About
all you can do is to check wiring for damage and
or bad connections, especially the ground wires.
There also may be a faulty switch.
Question:
1998 GMC Suburban mileage: 135,000.
We have a GMC Suburban 1500 SLT, which
has been great but has suddenly developed a
strange electrical problem.
The remote keyless entry stopped working.
When I checked the fuse box next to the
steering column, I pulled the appropriate fuse
for that (which also controls central locking)
and it looked OK.
But when I put it back in, it sparked and
wouldn't go back in.
I can drive the car fine, but it is a
pain without the keyless entry and central
locking.
I'm guessing there's a short somewhere; any idea
where the likely place might be?
Thanks.
Answer:
Scan the body control module for fault
codes.
This should pinpoint your problem.
Question:
2003 Toyota Camry mileage: 62,000.
I was changing my alternator with one
from my 1985 Camry parts car.
I forgot to disconnect my battery and the
alternator wire touched the engine and arced
out.
Now I have headlights and horn but that is it.
I have check fuses under dash in engine
compartment and fuseable links near
battery-circuit breakers.
Could I have fried the computer?
Does it have a computer?
When I turn the key on, all I get is the
idiot "charge" signal lit up.
What to do?
Thanks
Answer:
Check the power distribution relays.
You may have "shorted" one.
Question:
1999 Chevrolet 4 WD mileage: 137,000.
While driving down the road, the gauges
and speedometer quit working.
No voltmeter, gas gauge, oil pressure or
temp.
In addition, the service engine soon light does
not work.
Scanner will not communicate.
ECM fuses are not blown and have power at
them.
Fuseable links at back of alternator are not
blown and engine runs fine.
Please try to assist me.
Thank You.
Baffled -Elmer
Answer:
Check for wiring damage and faulty ground wire
connections.
Question:
1999 Chevrolet p/u 1/2 ton 4.3L mileage:
125,000.
Second time this has happened; the first time
several months ago.
I have been noticing that when I crank
the truck, it sounds like the battery is low or
the starter is dragging.
Last night the speedometer and tachometer
gauges were fluctuating at a steady speed.
When I would change from dim to bright
lights, both gauges would jump to the right
about a half-inch and immediately return to the
previous state.
Once the check engine light came on for a
few seconds.
This morning the truck acted as though
the battery was dead and I had to jump it.
The battery and alternator were checked
out to be ok.
Today the symptoms have all but
disappeared.
There still is a little dragging when
starting the truck, but not as bad.
Today I ran the truck with the lights on,
radio on, and fan on high, but no fluctuation of
the gauges.
The altimeter did seem to be little
further to the left of center than usual.
Thank you for any ideas
Answer: Electrical problems
are very difficult to find.
On your truck, we would check all the
ground wires.
From what you describe, somewhere there
may be a loose or bad connection.
You said the battery checked out okay,
was it load tested?
Question:
1997 Nissan Stanza
mileage: 130,000.
We have been having a problem with the
electrical system in the car.
The first symptom was the instrument
panel would go dead, the turn signals wouldn't
work, no gauges etc.
Then the battery light would come on for
a little while then the seatbelt light would
flash on then everything would start working
again.
No bulbs are burned out.
My husband has taken the whole thing
apart and can find nothing.
(He's pretty mechanically inclined) We
are completely stumped.
The only clue we have is that when you
put the car in reverse there are no back up
lights and the battery light gets brighter.
We have taken a voltmeter to all of the
wires in the steering column.
Any clues?
Answer:
Check the charging system and load test
the battery.
Check the main power wires for bad
connections.
Also, check the ground wires.
Question:
1995 GMC (Jimmy) mileage: 74,000. I'm
looking into a purchase of this 95 Jimmy from a
private owner. One odd thing is that the
electronic clock always stays lit. The
owner said this has always been like
that.
Is that true?
All my other GM vehicles the clock shuts
off when the ignition is turned off.
If I buy the vehicle as is, should I plan
on a visit to my local GMC dealer for a costly
repair?
Answer: The light in the clock
should go off with the key.
If the car is not driven for several
days, the battery may go dead.
We are not sure why the light is on and
have no idea what the cost of repairs would be
to trouble shoot the problem.
Question:
1997 Nissan 300sx mileage: 56,000.
My car battery won't hold a charge. It
starts when I jump it, it will stay charged as
long as I don't leave key in the ignition or
start it at least every four hours any more and
its dead, but like I said it starts right up
with a jump.
I had my battery tested and its fine.
Is this the alternator (which is 6 months
old) or the starter?
Answer:
If the car starts with a jump, the starter is
okay.
Was the battery load tested with the
proper equipment?
You may have electrical drain on the
battery with the key off.
Here is the procedure we use to isolate a
battery drain.
Remove negative battery cable from the
battery.
Using a 12-volt test light, hook one end to the
negative battery post the other end to the
negative battery cable you just disconnected.
The test light will glow or "light" if
there is a drain.
If the "light or glow" is faint, that is
probably normal draw for the clock or computer.
If the "light or glow" is bright, then there is
a large drain.
That should be corrected.
Now start removing and replacing the
fuses one by one until the light goes out; that
one will be the circuit with the drain.
Remember to hold in the button in the
door jam for the interior lights.
Question:
1999 Chevrolet Suburban mileage: 136,000.
I have an electrical problem.
I can't get the dash lights to work, and
when I change the fuse, it lasts about five
minutes and then blows again.
The buzzer would not shut off, so I
disconnected it.
I need help and fast!
PLEASE!
Answer:
After a discussion, we think the problem
may be a short in the plug for trailer lights.
(Hope you have a trailer plug) .
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