Blinker, Cigarette lighter and Radio Backlight Issue

[Salvagedcircuit]

I have been having a strange issue where my radio LCD backlight blinks whenever my turning signal is active. The cigarette lighter and radio are on the same circuit, so I measured the 12v rail. When the vehicle is off, the 12v rail fluctuates from 11.3v to 12.5v with the turning signal, and that correlates directly to the radio lcd backlight.
 

 

I have tested:
-Headlights. Issue persists regardless if I have LED or halogen front headlights. I have rear halogen bulbs.
-Cab lights. Issue persists regardless if I have the LED cab and footwell lights installed.
-Radio / clock illumination relay. Tests fine with 12v psu.
-Radio. Removed, makes no difference.

-Checked Fuses. Etr fuse is fine.
-Soldered and repaired the ~30 duct-tape crimps in the engine bay.
-Have not disturbed the C101 (because its mostly engine related wiring).

 

Details:

-I have a base comanche that never had a radio. No headlight sentinel either. Previous owner butchered the radio harness. I re-wired it and I believe it is correct, but I may be wrong. no wires are bridged to the radio connector, each wire is one conductor.

 

-The original ground wire for the radio was melted badly (wire jacket missing in sections). I insulated it with electrical tape and ran a new ground from G102 ground location (below steering column). My dash fascia is currently apart and I'm trying to trace any potential other damage this wire caused.

 

-The radio LCD backlight is operating correctly. The lcd backlight turns on when the vehicle is on and when the headlights are on, dims with the dimmer switch, which is correct as per the manual. When headlights are on and the radio backlight is out (dimming set to 0), the Cigarette lighter measures 14.5v.

 

-The flashers seem to still work, but either continue to work quietly or start flashing fast then go silent and stop working completely.

 

Possible culprits:

-wiring harness

-column turning signal switch?

-flasher?

 

I am looking over the 88 electrical wiring diagrams. If anyone has any input, I would gladly appreciate it. Thanks!

[Ωhm]

Ground G102 is connected to G103 via G4_C100 (Bulkhead). Check for damage.

[Salvagedcircuit]

23 minutes ago, Ωhm said:

Ground G102 is connected to G103 via G4_C100 (Bulkhead). Check for damage.

 

What is G4_C100? I know C100 is the bulkhead. What is G4?

Thanks.

[Ωhm]

4 minutes ago, Salvagedcircuit said:

What is G4_C100? I know C100 is the bulkhead. What is G4?

 

Pin location

 

[Salvagedcircuit]

Thanks for your input!

There is a 12awg wire at what looks like H4 to me and there is a brown/blk trace wire at g4.

The black wire measures 0.2ohm to c103, which is good. no signs of melting or corrosion near the connector in the bulkhead.

No signs of melting or corrosion on the back of the fuse panel either. There was a considerable amount of dust / foam around the two, so I blew out the whole area with compressed air.

 

 

 

 

It seems that source of the 12awg gnd is in good shape, I just have to find out where the 12awg splits into an 18awg gnd wire. that should be the location of most carnage. Any idea where to find point G? (page 57 of the electrical manual)

 

 

 

One other thing I noticed, are there supposed to be (3) ghost crimps on the wiring harness that goes to the steering column?

Edit: I have since soldered these up and insulated.

[Ωhm]

Page 91. Look for circle with a G in it. Circles indicate splice location, supposably. 

[Salvagedcircuit]

4 hours ago, Ωhm said:

Look for circle with a G in it. Circles indicate splice location, supposably. 

This I did not know. Thanks. I'll dig around a bit there. I'm trying to avoid removing the whole dash if possible.

[Salvagedcircuit]

I finished soldering up the ghost crimps and I tried some newly produced thermal flashers. I noticed that the voltage drop was about 0.5v now instead of about 1v with my old thermal flashers. The newly manufactured flashers also blink rapidly but at least consistently.

 

I'm going to go grab an electronic led flasher and see if that resolves my issue. Is it possible the blinking issue is related to the column turning signal switch?

[Ωhm]

The Fuse Panel (pg8) shows three (3) fuses using the same busbar (Blower Motor-Turn B/U-Radio). Busbar might need a visual inspection (common point). Does voltage fluctuate on all three fuses when KEY ON and TS is ON?

[Salvagedcircuit]

On 7/26/2024 at 10:09 AM, Ωhm said:

The Fuse Panel (pg8) shows three (3) fuses using the same busbar (Blower Motor-Turn B/U-Radio). Busbar might need a visual inspection (common point). Does voltage fluctuate on all three fuses when KEY ON and TS is ON?

When the key is in the accessory position and the turning signal is on:

+- 0.5v

-Blower Motor

-Turn B/U

-Radio

+-0.3v

-power accessory
-trans fuse
-gauges

 

 

When the key is in the engine-on position and the turning signal is on:

+- 0.5v

-Blower Motor

-Turn B/U

-Radio

+-0.3v

-power accessory
-trans fuse
-gauges

 

*voltages are referenced to G102 gnd location, below steering wheel.

[Ωhm]

Busbar is supplied with voltage from the IGN SW (C267_A). Circuit has been known to have issues. IGN SW & circuit can carry high current flow rates. Check both.

 

@Rooster92

 

 

[Salvagedcircuit]

30 minutes ago, Ωhm said:

Busbar is supplied with voltage from the IGN SW (C267_A). Circuit has been known to have issues. IGN SW & circuit can carry high current flow rates. Check both.

 

@Rooster92

 

 

 

Thanks. I checked these last night. both connectors are clean and don't look melted. However, the (3) ghost-crimped wires were attached to 3 of the wires on these two connectors. I have since soldered them up and repaired them properly

I am currently removing the front most dash cowl to try and access the wireloom that goes to the radio and inspect for damage.

The phillips screws they used are really hard to get to, especially the driver side one.

I'm hoping to cut the wire zip-ties that hold on the wire loom and move them down to the gauge cluster area where I should then be able to inspect the wires individually.

[Salvagedcircuit]

I was able to access the portion of the wire loom from the 12awg to the 18awg wire that was designated for the radio. The wire melted together with several other circuits along the wire harness behind the dash. I cut the wire at the lovely (7) 18awg wire-to-12awg duct-tape crimp and removed the melted wire from the wire loom. I was just able to get to the wiring harness by removing the front cowl, cutting some zip ties and finagling the wire loom into the gauge cluster area.

Unfortunately, despite removing this melted wire, the same problem persists. Nothing changed, it's still +- 0.5v and +- 0.3v on the same circuits as above. I tested with other turning signal flashers and the same results occur.

 

 

[Ωhm]

I wonder if other MJ's have similar issues with Radio backlighting when TS are ON. Anyone, looking for feedback. Could this be normal?

[Salvagedcircuit]

17 minutes ago, Ωhm said:

I wonder if other MJ's have similar issues with Radio backlighting when TS are ON. Anyone, looking for feedback. Could this be normal?

 

It is possible that this is not an actual issue. +-0.5v is not the end of the world. I do wonder if other folks have +- 0.5v on their cigarette lighter when the flasher is enabled. If anyone tests, be careful when you probe, I've shorted (2) 15a fuses by not being steady with my probes.

 

I posted about this issue a few months back, but I did not realize it impacted multiple circuits. It seems @eaglescout526 had a similar blinking issue.

I wonder if it's normal for renix XJ/MJs.

[eaglescout526]

1 hour ago, Salvagedcircuit said:

I posted about this issue a few months back, but I did not realize it impacted multiple circuits. It seems @eaglescout526 had a similar blinking issue.

I wonder if it's normal for renix XJ/MJs.

Yeah, its still around. I dont notice it much anymore but I take it into fact that you have three bulbs blinking at once can be hell of a demand electrically. I imagine if you went to LED the issue would go away. Given how both XJ and MJ are wired and alot seem to share the same ground wire at a splice in the dash, in the engine bay and at the chassis, theres bound to be a some other circuits affected.

Its like when a high demand appliance like an AC in your house can make the lights dim for a second and back to normal after the appliance is running. 

[GonzoTheGreat]

13 hours ago, eaglescout526 said:

three bulbs blinking at once can be hell of a demand electrically. I imagine if you went to LED the issue would go away

I second that. A few bulbs isn’t much by todays standards, but when you’ve only got 60 amps from the alternator, and questionable aging grounds, it adds up.
 

I used to have the same problem, but I’ve gone LED with every bulb except the front directionals. They had to stay incandescent to make the late-model turn signal mod work, and now I have electronic flashers to work with the LEDs. I also replaced the front turn signal sockets and headlight switch, and cleaned up/improved all my grounds. I also installed a headlight relay harness, but I don’t think that affects the directionals. 
 

I'm not sure which of these things fixed it, but the radio doesn’t dim anymore. I wish I could be more helpful, but I did everything in one go, so I couldn’t tell you what was the exact culprit. 

[Salvagedcircuit]

It is possible that this is not really an issue and amc / renault treated the flasher as a "temporary state" and did not compensate for the flasher on the flasher circuit.

The new electronic flasher is substantially louder than my thermo flasher and I will be reducing the taillight / marker light current load when I go to LEDs, which should be soon enough. I'll update this here again when that time comes. Thanks again everybody, special thanks to Ohm!