Idle RPM sensitivity to signalling?
 

I have a 95 Grand Prix GTP, and if I'm signalling at idle (in gear, my
foot on the brakeat a dead stop) my RPM decreases by about 50 RPM when
the signal light is lit and cycles back up when it turns off and
continues during the periodicity of the signalling. My dash lights also
slightly dim with the same trend. My question is, is this normal?
Should the engine idle and interior accessory lights really be this
sensitive to such a small electrical draw? I have checked my battery at
idle and it's charging at 13.8V, and I haven't had any other electrical
problems. However, I do have some other erratic idling when not
signalling, so if this could all be attributed to the same electrical
problem I'd love to figure it out. Thanks.

407

Idle RPM sensitivity to signalling?
 

Aaron407 wrote:
> I have a 95 Grand Prix GTP, and if I'm signalling at idle (in gear, my
> foot on the brakeat a dead stop) my RPM decreases by about 50 RPM when
> the signal light is lit and cycles back up when it turns off and
> continues during the periodicity of the signalling. My dash lights also
> slightly dim with the same trend. My question is, is this normal?
> Should the engine idle and interior accessory lights really be this
> sensitive to such a small electrical draw? I have checked my battery at
> idle and it's charging at 13.8V, and I haven't had any other electrical
> problems. However, I do have some other erratic idling when not
> signalling, so if this could all be attributed to the same electrical
> problem I'd love to figure it out. Thanks.
>
> 407

Do you mean that the directional signals cause the idle to drop, or
that the brake lights cause the idle to drop? if the latter I would
actually suspect a vacuum leak in the brake booster.

nate

Idle RPM sensitivity to signalling?
 

The car is an automatic, and if I'm sitting stopped with my foot on the
break, in gear, signalling at a stop light for example, the RPM
fluctuates with the periodicity of the signal light. If I merely shut
my signalling off the erratic idling stops. Does that clarify anything
or did I basically just repeat what I just said? Hopefully it helps...

407

Idle RPM sensitivity to signalling?
 

So you have all the electrical accessories on. Do you have an after
market radio with hi wattage amp? I think you are just seeing the load
that a fully loaded alternator can put on an engine.
Stan

Aaron407 wrote:
>
> I have a 95 Grand Prix GTP, and if I'm signalling at idle (in gear, my
> foot on the brakeat a dead stop) my RPM decreases by about 50 RPM when
> the signal light is lit and cycles back up when it turns off and
> continues during the periodicity of the signalling. My dash lights also
> slightly dim with the same trend. My question is, is this normal?
> Should the engine idle and interior accessory lights really be this
> sensitive to such a small electrical draw? I have checked my battery at
> idle and it's charging at 13.8V, and I haven't had any other electrical
> problems. However, I do have some other erratic idling when not
> signalling, so if this could all be attributed to the same electrical
> problem I'd love to figure it out. Thanks.
>
> 407

Idle RPM sensitivity to signalling?
 

I do indeed have an aftermaket stereo with fairly decent capability of
power drain (~600Wrms), but this problem arises whether the stereo is
on or not. Last night for example, I had this problem and the stereo
hadn't been on for at least 20 minutes of driving, so I would think
that the battery should have been recharged fully by this point. But
please keep firing away with possible causes, I really appreciate any
help.

407

Idle RPM sensitivity to signalling?
 

Does this same problem happen during the day when the headlights are not
on? I would guess not. At night when this happens at a stop, put the
trans. into neutral and see if problem goes away.
Stan

Aaron407 wrote:
>
> I do indeed have an aftermaket stereo with fairly decent capability of
> power drain (~600Wrms), but this problem arises whether the stereo is
> on or not. Last night for example, I had this problem and the stereo
> hadn't been on for at least 20 minutes of driving, so I would think
> that the battery should have been recharged fully by this point. But
> please keep firing away with possible causes, I really appreciate any
> help.
>
> 407

Idle RPM sensitivity to signalling?
 

I just assumed that since the car has daytime running lights that it
wouldn't be much different at night unless I used the highbeams.
Anyway, I have noticed that when I put it into neutral the problem does
go away as the engine is under less load. Out of curiousity, at night
without the highbeams and A/C off, approximately how much power should
all the accessories (including the daytime running lights and
aftermarket stereo) consume? I guess small electrical problems like
this could possibly be attributed to this draw and the cheap Canadian
Tire battery I have.

Idle RPM sensitivity to signalling?
 

Sorry, I meant -excluding- the aftermarket stereo.

Idle RPM sensitivity to signalling?
 

I have seen that when the body loses it's ground.

The GM's usually have a mesh strap from the bell housing to the body
with a small black wire from the battery post to the body. When the
mesh strap goes, the small wire will be severely overloaded and will
usually start to melt the insulation before it burns up and the vehicle
dies.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Aaron407 wrote:
>
> I have a 95 Grand Prix GTP, and if I'm signalling at idle (in gear, my
> foot on the brakeat a dead stop) my RPM decreases by about 50 RPM when
> the signal light is lit and cycles back up when it turns off and
> continues during the periodicity of the signalling. My dash lights also
> slightly dim with the same trend. My question is, is this normal?
> Should the engine idle and interior accessory lights really be this
> sensitive to such a small electrical draw? I have checked my battery at
> idle and it's charging at 13.8V, and I haven't had any other electrical
> problems. However, I do have some other erratic idling when not
> signalling, so if this could all be attributed to the same electrical
> problem I'd love to figure it out. Thanks.
>
> 407

Idle RPM sensitivity to signalling?
 

Thanks, I'll have to check that out!