Intermittent electrical problem

[sario]

Twice now my 97 legacy outback has had a problem where the wipers, dash lights, and radio stop working or start going really slow.  Although car runs fine, and the head lights still work.  As soon as I turned the car off and on again everything started working both times.  So far I've had the alternator tested, the battery checked, tested and cleaned any grounds i could find.   Does anyone an electrical schematic of the exsesories they could send me, or any suggestions on what to check.

[mwatt]

Unless the alternator belt is way too loose, the alternator itself is failing.

Edited December 31, 2013 by mwatt

[ivans imports]

check bottom of under hood fuse box for corroded wires have had 2 with problems there in last cupple weeks

[sario]

Unless the alternator belt is way too loose, the alternator itself is failing.

 

Do alternators usually fail intermittently like this?   I'm not saying that this isn't the problem. I just never taken the chance to look at a wiring diagram for a car before.  I thought the battery was in parallel with  the alternator, and if that's the case, wouldn't the battery have to drain down before the accessories stopped working?

[sario]

check bottom of under hood fuse box for corroded wires have had 2 with problems there in last cupple weeks

 

Thanks for the tip. I took a look, and  It doesn't look like thats the problem in this case.

[Fairtax4me]

There's no connection between any of those circuits unless you go all the way back to the main fuse box.

 

This is probably a poor connection somewhere. It could be a bad ground connection to the battery, or a poor connection of the chassis ground wire. (The small wire off the negative cable)

 

Could also be poor connection through the SMJ connector where all the wires come through the firewall going to the dash fuse panel.

 

Definitely check the battery connections very well. Make sure the terminals on the cables slide all the way onto the battery posts. The top of the post should stick out above the terminal.

[sario]

There's no connection between any of those circuits unless you go all the way back to the main fuse box.

 

This is probably a poor connection somewhere. It could be a bad ground connection to the battery, or a poor connection of the chassis ground wire. (The small wire off the negative cable)

 

Could also be poor connection through the SMJ connector where all the wires come through the firewall going to the dash fuse panel.

 

Definitely check the battery connections very well. Make sure the terminals on the cables slide all the way onto the battery posts. The top of the post should stick out above the terminal.

 

 

The SMJ connector sounds promising.  I was starting to suspect the Ignition

switch, but that connector sounds more likely. I already gave the battery post, battery terminals, and grounds a thorough cleaning.

 

 

 

 

[Cougar]

The items you mention having trouble are supplied power through the ACC contacts of the ignition switch. That would be my top suspect for this problem especially since you say cycling the ignition switch clears the problem. You should be able to monitor the voltage at the fuses in the dash and compare that to the input lead to the ignition switch to verify this. The input wire to the switch might be white/black possibly.

[Fairtax4me]

I thought ignition switch too, except the dash illumination lights aren't supplied power through the switch. The switch provides power to the control side of the tail & illuminatin relay, but the load side comes straight from the battery.

I'm still trying to make sense of just how the illumination module works (have been for months), but I don't see how how a voltage drop at the ignition switch would cause the dash illumination lighting to dim, since those lights get power directly from the fuse box.

 

If its the warning lights (CEL, Seat belt, battery/charge, low fuel, etc.) that are dimming, then yes, most of those are powered directly by the ignition switch and would be affected if the switch had a poor contact. But those generally aren't lit except when first starting the car.

[sario]

I replaced the Ignition switch assembly yesterday.  On the old one I checked all the contracts resistance, they all seemed fine.  But, while checking I did notice if i turned the key back gently from the start position it wouldn't always fully return, and I'd get a poor connection.  I think the switch assembly was the problem, and I'll post back later if it turns out different.

For reference Intermotor brand replacement switch I use is made by the same manufacture as the OEM one.  It was about $50 cheaper as well.

Thanks for everyones help.

[Cougar]

Fairtax4me
"I'm still trying to make sense of just how the illumination module works (have been for months), but I don't see how how a voltage drop at the ignition switch would cause the dash illumination lighting to dim, since those lights get power directly from the fuse box."

 

 

I at first thought that the power for the dash lights did pass through the ignition switch but you are correct, power comes from the main panel, through the taillight relay, and then to the lights. I suppose the relay contacts could be causing a slight change in voltage drop due to a voltage change in the supply voltage to the relay coil. Another possibility pehaps is there may be a change in the ground reference to the illumination control module due to the added loads.

[sario]

Fairtax4me

"I'm still trying to make sense of just how the illumination module works (have been for months), but I don't see how how a voltage drop at the ignition switch would cause the dash illumination lighting to dim, since those lights get power directly from the fuse box."

 

 

I at first thought that the power for the dash lights did pass through the ignition switch but you are correct, power comes from the main panel, through the taillight relay, and then to the lights. I suppose the relay contacts could be causing a slight change in voltage drop due to a voltage change in the supply voltage to the relay coil. Another possibility pehaps is there may be a change in the ground reference to the illumination control module due to the added loads.

 

It's also possible I misremembered what happened,   I don't think I did, but it's definitely possible.

 

I'm an electrician in a hydroelectric power plant,  I do a lot of troubleshooting on problems other people tell me about.   One of things I've learned to do is verify, when possible, everything thing i'm told and redo any trouble shooting by other electricians.   It's surprising how often people unintentionally lead you down the wrong road.

[Cougar]

 

It's also possible I misremembered what happened,   I don't think I did, but it's definitely possible.

 

I'm an electrician in a hydroelectric power plant,  I do a lot of troubleshooting on problems other people tell me about.   One of things I've learned to do is verify, when possible, everything thing i'm told and redo any trouble shooting by other electricians.   It's surprising how often people unintentionally lead you down the wrong road.

I know what you mean.

 

You're not at Ross Dam by chance are you?

[sario]

No,I've seen pictures though. Neat looking dam.

[Cougar]

It is. The dam and the area it is located in is incredible. Though I don't know how they can get though the winters there.

[Olnick]

"Though I don't know how they can get though the winters there," says the man from Alaska!!!

[Cougar]

"Though I don't know how they can get though the winters there," says the man from Alaska!!!

LOL. Yeah, we have a long winter season here in Anchorage but don't have a huge amount of snow to deal with usually. Ross Dam is located high in the Cascade Mountains and I can't imagine what their average snowfall is during the Winter. It sure is pretty country though. There is plenty of info on the web about it if your interested in checking it out. You probably don't get to see many snow flakes where you are at Olnick. 

[Olnick]

Yeah, have driven the North Cascades Highway (SR 20) and it is absolutely beautiful up there.  No snow flakes but we had hail pounding our skylights a month ago--have lived here 50 years and that was the first time I ever heard that!