Alright so, I’ve been trying to figure out why when I turn on my fogs, rear defroster, headlights, Temp fan, hit brakes ect… my idle will drop a few hundred rpms. If thy are all on the car will even shudder. I knew my battery was bad so i replaced that (voltage output was fine but the thing would die if I left the lights on for even 2 minutes. It was like this when I got the car…) That didn’t have any effect on the dropping idle.
So then reading threads here and by FCM’s advice I checked my fuses (only visually inspected) and re-ran the stock grounds from the battery posts to the chassis to the trans as well as from the rad mount to the valve cover…But that didnt seem to have any effect either. Car still drops rpm’s when under heavy electrical load. Even just lighting up the brakes will have some effect.
Now to make matter worse I’m having all sorts of connected problems. As in, sometimes when I go to turn on the heat the fan will barely run and my passenger side headlight will dim. Also on my speedometer the right turn signal light will illuminate as will the high beam light faintly. Then when I turn on the wipers they will go up fine then return ridiculously slowly. FCM has said that this is normally a grounding problem but how on earth do i find it?
Any help is appreciated…I am at a loss.
EDIT I just noticed someone on the next page was having the same problem with the idle dropping and that FCM recommended also checking/cleaning the leads from the starter and alternator to the battery. This I will do…I will say again though that with everything i did today really cleaning all of the grounds and contact points well it made no difference at all in my case.
Don’t forget the pos.(+) side, all the connections from batt. to fuse box and from alt. to fuse box and the main fuses themselves.
I would also check plugs going in and out of the under dash fuse box, make sure there is no corrosion on the metal pins, and make sure they are plugged in properly.
You will also find dash harness grounds around the drivers “A” pillar, [around under dash fuse box, there are probably more on the pass. side.
Bad dash harness ground will cause the kinds of symptoms you are experiencing, turning on one thing having an effect on something else.
Have you had a proper load check done on the car yet?
If not, have one done, it is free at just about any alt./batt. shop and only takes a few min. to do. 94
Don’t forget the pos.(+) side, all the connections from batt. to fuse box and from alt. to fuse box and the main fuses themselves.
Will do. I did clean pos batt. terminal but will check those at under hood fuse box as well.
You will also find dash harness grounds around the drivers “A” pillar, [around under dash fuse box, there are probably more on the pass. side.
I will have a look around though Im not sure I would be able to identify them if I saw them.
Bad dash harness ground will cause the kinds of symptoms you are experiencing, turning on one thing having an effect on something else.
Is it possible that my crappy alarm system install is causing this? i dont know if you rememeber but I still have that Viper installed with the T connectors you dont like. I hadn’t had any more problems really until lately so I didn’t remove it and repair the wires like you said.
Have you had a proper load check done on the car yet?
I was waiting to re-do those grounds and check connections before I had it tested. I just did that today so Im guessing that should be my next move? Or do you think I should uninstall the alarm system THEN have it checked?
Thank you as always FCM…With winter coming on and lots of wet weather i really need to get my blower/heater/wipers working properly.
Dash harness grounds are bolted to the cars chassis, 1 or more black leads on one ring terminal or more then one ring terminal bolted, [10mm bolt] to chassis.
If these bolts are loose or connection is poor for any reason, circuits will ground through each other, [switching one circuit has an effect on another circuit].
Yes it is possible the alarm install is causing problems, less likely if alarm is working properly, however Ttaps can damage wiring, I have seen/repaired wires that the Ttap had cut all but one or two strands of the wire the tap was installed on.
Yes, “uninstall the alarm” repair any damaged wiring, if the Ttap has cut through any strands strip a little insulation, [1/8" or so] from either side of tap cut and hit wire with a little solder, it will reconnect any cut strands, cover with liquid tape.
A proper load check is kind of pointless if you have poor power or ground connections, check/redo them first then have the load check done.
Sometimes a load check is not needed, [although it can’t hurt] once power and grounds have been done as it was a connection problem, we see this almost every day at the shop, customer comes in with older car and your type of symptoms and wants use to check batt./alt. or “fix whatever is wrong”, we spend an hour or more redoing power and ground connections, [@ $80 hr] to find that all that was wrong was a poor ground or power connection. 94
So this morning on my way to work while the problems were still occurring, I was engaging and disengaging the fog switch and noticing that a click/fizzle sound was coming from the right side passenger foot well. I isolated it to the DRL relay and removed it. Lo and behold…AC fan worked again, wiper stopped being retarded, and everything else seemed fine.
SO…Problem 1 was My DRL relay is fried, I’ll find another one somewhere and get that straightened out. You were obviously on the right track telling me that something under the dash was causing a short or ground problem.
As for Problem number 2, removing the DRL relay had NO effect on my idle bogging when I put a load on the electrical system. And the system is only ever effected when Im idling…Car runs beautifully at all other rpm’s so it does seem more and more like my alternator is on the way out. Not hard to believe really it is most likely original and the car is almost 20 years old. I checked the rest of these power/ground leads and they look really clean so I am going to see into an alternator/charging system test next.
On to problem 3… :S
When I turned on my headlights to make sure they were working, I still had the problem with the passenger side being much dimmer than it’s supposed to be. (Car not running) Basically all of my lights on the pass side front (both turn signals, headlight, and fog) were all very very dimly lit. (Its worth noting at this point that this car is a rebuild from front end damage.) So I wiggled some wires running along the fender and the headlight got brighter, side signals stopped being dim and just returned to normal off, but fog light didnt work. So each time I would turn the fog lights on this scenario would return and I would wiggle the wire and eventually it would stop. Then seemingly for no reason the fog came on again and everything is working as it should at the moment.
So it seems I have some sort of loose/cut wire in the pass side harness and possibly a bad fog switch as well?
Definitely a connection problem with the lights, again either with the power or the grounds, I would find and check the pass. side lights grounds, look in the area where you “wiggled some wires”, the fog light will also be a connection problem, it will not be the switch, all the switch is doing is turning on the fog light relay and the fog lights are common after the relay, [one output lead that is split to the left and right sides, the problem has to be with the pass. side fog light. 94
Are all of those power leads and grounds initially carried to the lights in the bundle of wires that make up the harness and travel along the fender in the engine bay? Cuz thats what I wiggled…the harness itself. The harness has some sort of protective plastic rectangular casing thingy about 6 inches long between the battery and the fuse box that looks like it was split or nipped and cracked…Possibly in the accident.
Perhaps I will snap a photo and show you what i mean.
Here’s the part of the harness i was talking about. If your standing at the front of the car its to the left of the airbox and runs along th fender toward the under hood fuse box.
The part circled in yellow is the pastic thing I was trying to describe and also was the part I wiggled to seemingly get the short to stop. The part circled in red is the “cut” section…Damage i believe to be caused by the major front end collison the car was in before i got it.
I hadn’t had any more problems really until lately so I didn’t remove it and repair the wires like you said.