Gremlins in the wiring: Need help with loud buzz from radio & dim instrument panel - JeepForum.com
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Unread 09-13-2013, 12:04 AM   #1
Asouthern
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1995 ZJ 
 
Join Date: Jul 2012
Location: Nashville, TN
Posts: 18
Gremlins in the wiring: Need help with loud buzz from radio & dim instrument panel

I have been having an intermittent problem for the past month or so with my 95 ZJ and the radio/instrument panel lights. I would like some advice for my next steps in troubleshooting/what to check next toward finding a resolution and any experiences with similar problems.

Background Conditions: Daily driver, but has been sitting for a week or two at a time not running since July.
- just replaced the headliner (all lights/sun visors work properly) although problem predated headliner replacement
- heater core was replaced 2 years ago
- stock radio was rebuilt 6 ish years ago
- driver side door power windows rewired 1 year ago
- ac/heater control unit was replaced 1-2 years ago, panel unit's lights have never worked.
- the brake lights would not turn off 2 weeks ago after car was turned of/key out of the ignition. This occurred after driving with the dim lights/buzzing. The brake lights now turn off when the car is off.

Problem: The clock will dim/flash usually within 2 minutes of startup/driving. This will either be the end of it and return to normal conditions (instrument lights ok, radio ok) or devolve into chaos. The instrument panel lights & clock will dim out almost completely while driving (with or without headlights on). The radio will cut out and then produce a sound one might hear standing front row to the amp tower at a metal concert. It doesn't matter the volume of the radio, the speakers produce a loud buzz regardless. With the radio turned off it has even produced quick buzzes through the speakers. All interior lights, power locks/windows, headlights, wipers, and gauges work fine. The dimmer switch does too when the lights are not acting up.

First steps:
- Checked battery, terminals were in bad shape. Replaced terminals, ensured continuity with new connections. First startup after new terminals, dim light/buzzing did not occur. Problem returned today.
- Checked #8, 10, and 24 fuses all are a-ok
- Searched the forum and read 94 ZJ electrical issue, before I rewire this, fun and games with alarms and radios, but to no avail for issues with the radio/dim instrument & clock lights (sans interior lights/wipers/aftermarket sound systems etc)

Sorry if it's a bunch of info, but I tend to err toward too much rather than not enough. I'm all ears as to suggested next steps toward locating the culprit. Thanks.

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Unread 09-13-2013, 04:13 PM   #2
gearheadnick
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1997 ZJ 
 
Join Date: Mar 2012
Location: Tunkhannock, PA
Posts: 595
My first thought is to pull the radio and inspect all the wires for damage/loose connections. It kinda sounds like a ground problem. You could add your own ground wire, even if it doesn't solve the problem, it won't hurt to have.
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Unread 09-14-2013, 05:38 PM   #3
Asouthern
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1995 ZJ 
 
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Location: Nashville, TN
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Thanks. I'll take a look into doing this. Having not pulled it out, is it as simple as splicing into the current ground in the harness or should I make (is there) a location on the back of the unit to attach it and then run to the frame? (like the vent holes in this 05 GC unit)

If you don't know that's alright, I just thought I'd ask before taking stuff out and then having to run to the store.
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Unread 09-15-2013, 06:15 PM   #4
gearheadnick
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1997 ZJ 
 
Join Date: Mar 2012
Location: Tunkhannock, PA
Posts: 595
On a radio that's already installed, I usually splice in a wire on the ground wire reasonably close to the radio and run the wire to a known chassis ground. Sometimes you have to hunt around behind the dash, but I usually find a stud above the brake pedal to attach my new ground to. Any nut or bolt that's on the firewall will do, just make sure you clean up the mating surfaces with a file so you give the best possible electrical connection.
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Unread 10-20-2013, 11:48 PM   #5
Asouthern
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1995 ZJ 
 
Join Date: Jul 2012
Location: Nashville, TN
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Ok, so here's a month update. The issue went intermittent again for a while. However last weekend the radio started acting up a lot. The gremlins will make their buzzing and if the radio is cut off after a period of time (sometimes 10 minutes to an hour) normal function will *usually* return. This affects both AM and FM bands.

Work done: I spliced a new ground into the sidewall from the radio and checked for continuity (a-ok). I also took this time to take out the dimmer panel and inspect the solder on it. Each ground I checked was also good with continuity on the dimmer circuit board. I also checked the interior antenna connection (not through the sidewall) near the passenger floorboard while the buzzing was occurring. No change.

When the radio goes out/starts buzzing, I have not experienced the dash lights flickering recently (2+ months). The functioning dimmer panel rules out this culprit. Since the issue is rather consistent in lengthy episodes now, I was able to record the sound that is coming from the radio. Take a listen to the song of the gremlins' people here. It should be noted that the volume is only turned to the second notch from the off position, yet the buzzing is at this volume consistently regardless of how I adjust the volume knob. Off is the only solution to make it stop/not go insane while driving.

If anyone has any thoughts as to next steps I'm all ears.
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Unread 10-21-2013, 11:15 AM   #6
Compgeek789
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1994 ZJ 
 
Join Date: Jul 2011
Location: Conway, New Hampshire
Posts: 197
Have you checked out the connections to the battery terminals, and the positive feed to the radio or dirt/looseness? Also, when it buzzes and the dash lights flicker/dim, is there any difference in the engine's operation, such as minor drops in RPM?
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Unread 10-21-2013, 04:57 PM   #7
Asouthern
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1995 ZJ 
 
Join Date: Jul 2012
Location: Nashville, TN
Posts: 18
Checks performed:
- battery terminals ok. Voltage reading 10v from battery on handheld meter w/engine off, 12v? (the gradation lines are non-sensical from 9-14) on dash w/key to accessory, 14v on dash w/engine running. Battery was load tested a month ago and reported fine.
- antenna re-checked (per service manual) and passed all 4 checks. Note: buzzing occurs with/without antenna plugged in
- when a tape is inserted to the deck loud buzzing stops but no sound (or perhaps the gremlins are momentarily appeased with my Motown tape)
- intermittent buzzing/zap sound while key is in ignition w/engine & radio off

- continuity checks on feeds: circuits refereed from service manual, voltage drops tested from fuse-radio ground
(red/grey cable from ignition switch) has continuity b/w connector and fuse #10 [9-10V drop]
(red/white from F60 splice-always on circuit) has continuity b/w fuse #8 [9-10V drop]
(blue/red from L90 splice-headlamp dimmer circuit) has continuity b/w fuse #24 [0V drop/toggle off, 10V drop/toggle on ]
(orange from E2-instrument illumination circuit) traced to instrument cluster [ZJ 69 in electrical section of SM] but not sure where it goes from there (any ideas?)

Compgeek: Lights haven't flickered in over 2 months but I can't recall any noteworthy RPM loss
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Unread 10-22-2013, 03:03 PM   #8
Asouthern
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1995 ZJ 
 
Join Date: Jul 2012
Location: Nashville, TN
Posts: 18
Thanks for all your suggestions. After another inconclusive circuit test I took the head unit to a radio guy and he isolated the problem to the unit itself.

His response was "I've never seen one do that before" and he's been at it for quite some years. So if you have a unit doing something similar...now you know. Although the initial concurrent dimming of the instrument panel 3 months ago is still somewhat suspect. I will watch for the return of those gremlins.
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Unread 10-22-2013, 08:42 PM   #9
Bullwinkle_98ZJ
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1998 ZJ 
 
Join Date: Sep 2013
Location: Lafayette, LA
Posts: 57
I hope you find your electrical issue.

Speaking of Gremlin's, I wanted one for years when I was younger, but ended up with an Eagle, man what a GREAT car. Had the ZJ for over 10 years now.

Watched your sound clip...................RIGHT SIDE DRIVE ZJ
............I would love to have one of those.

Once again................... GOOD LUCK.
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Unread 10-22-2013, 11:10 PM   #10
Asouthern
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1995 ZJ 
 
Join Date: Jul 2012
Location: Nashville, TN
Posts: 18
Ah thanks for the props! I'm also sorry to disappoint but I took the video using my laptop and it didn't auto correct itself, so it's actually a standard left side drive zj.

But you are 100% correct, a right side drive zj would be nice (although some parts would be a pita to obtain for sure!).
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Unread 10-24-2013, 11:13 AM   #11
Compgeek789
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1994 ZJ 
 
Join Date: Jul 2011
Location: Conway, New Hampshire
Posts: 197
I wish I still had my original radio, but mine came with an aftermarket. I hope you can fix it.
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Unread 10-24-2013, 01:11 PM   #12
Asouthern
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1995 ZJ 
 
Join Date: Jul 2012
Location: Nashville, TN
Posts: 18
Alright here's the explanation of what was happening:

The radio power circuit (within the unit) contains several capacitors that use a corrosive (ammonia based?) fluid. Over time this fluid can leak out and erode the copper on the circuit. In some places the circuit runs were completely eaten away. The fluid (because it contained the eroded copper in solution) was able to maintain intermittent continuity within the unit.

The fix is to replace the capacitors and repair the circuit runs. The radio (of mitsubishi make) is 18 years old and supposedly these issues are more common on 85-90 radios in other models (fords, etc).

Again thanks for everyone's help and suggestions. I hope this will help another troubleshooter in the future (if they actually search for it).
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buzzing , electrical issue , instrument panel , radio

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