2nd Gen Non-Engine/Transmission Question about Radio

Years ago I was in a front end accident, and after getting the truck back, I discovered the display on the radio didn't work, but the radio worked and you could scan for stations and lock in stations with the button. Rather than hit the shop up about it, I just worked around it.

I don't drive the truck much so sometime last fall discovered that only the rear speakers were working! We have ground squirrels around here but it seems odd that wiring for both front speakers would be affected by chewing IF they were somehow able to get in the dash.

I am prepping the truck for sale and ordered a replacement radio from a salvage yard, but I am wondering if anyone can tell me what else might cause this kind of malfunciton? Hoping that the "new" radio will take care of the problem. It's the one with CD/cassette/equalizer.

 

Some questions:

• What year is the truck? I have a 1996 with a 1997 radio that plays cassettes and has an equalizer, but not CDs. But it has a CD controller head for a remote CD changer deck.
  
• Did the radio work OK before the wreck and body work? I am guessing yes.
• What model radio is it? Some high-end OEM radios had peculiar security features that caused bugs and gremlins.
• Have you tried a forum search? I have a vague memory that this isn't the first instance.
• Have you had the radio out to check connections? There are plugs at the back of the radio and one may be loose. Similarly, the wires going into the plugs may have backed out of the connector plug.
  
• Do you have a Factory TSM with wiring diagram? If you do, that can save you a world of wasted effort.

 

I apparently have the Infinity system with tweeters and they also aren’t working.

Yes, before the accident everything worked fine.

I got a tested stock replacement since posting and have the same results, so the unit itself isn’t the problem. I didn’t see any problems with the wires at the plugs.

I don’t have a wiring diagram and have searched all over for threads with the same issue with limited success. So far I have taken the door panel off on the driver’s side and checked ohms on the speaker itself and got a reading of 4 so apparently good? I saw one thread about checking from the plug end. Stretching my competency…Someone mentioned amps at the speaker end and my mind is blowing…but because the tweeters are also silent I’m doubtful that is the problem.

 

How many wires are going to the door speakers? If more than 2, then the speaker has a built in amp. Is there any separate component that looks like just a heat sink with wires going into it? This would be the amp for the system and you would need to check for power going to the unit. With a front end collision, the TIPM (fuse box) could easily been damaged , not allowing power to the amp. I have a Hayes repair manual, will look to see what I can find in it with regard to the radio/speakers.

 

Not sure of the year you have but in my 2002 Gen 2 wiring schematic there is a Radio Choke relay that supplies voltage to the amplified (premium) audio circuits for both front doors and pillar tweeters.

Since you infer the rear speakers are functioning can you activate the radio steering wheel switches to adjust the volume, switch stored stations and/or advance/reverse next available tunable stations? If not, much deeper troubleshooting is needed.
The radio supplies the voltage to activate the Radio Choke Relay which is grounded at G100, located at left front fender area under the hood near the windshield washer fluid bottle. If that ground were bad several other items could be affected like the heater fan. Something to check to see if a ground wire got disconnected/damaged during your accident repair.

In the Keep It Simple Stuff (KISS Principle) category...
Verify the 10 Amp Fuse 4 in the Junction Block is OK first. It protects/supplies the power through the relay's contacts to the built-in front door speaker amplifiers.

Aaargh! I re-read your first post...yet again...and refreshed my flickering brain cell where you stated the display was inop...off to the schematics again...

Relay's location...

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Excerpts from the 1996 TSM. For best results go to https://www.genosgarage.com/category/dodgeram-factory-service-manuals/a and buy the TSM that is correct for your year. It will have the actual wiring diagrams. The manuals are not cheap. But after a short while, finding the answer is worth the cost.

 

I'm sorry but no help with the manual that I have. Not one wiring diagram of the radio. Be more of getting correct manual as @Matt42 suggests. Other then that, a wiring toner to trace wiring would be the next best idea. Wiring can make you want to pull your hair out! I understand that you're trying to sell the truck, include the manual and add to price of truck!

 

Totally agree IF keeping the truck. Since he is preparing to sell the investment may not be warranted, or buy it to include with the sale to sweeten the deal.

 

My experience with the Haynes and Chilton manuals is that they include everything except what I need. Without exception, when it comes to wiring diagrams, they all have some disclaimer that says to the effect of, there are so many wiring diagrams and variations that the reader is advised to consult factory sources. Well, duh. Why did I buy their manual in the first place. This is why I bought the factory service manual for every vehicle I have ever owned, even if it was horrifically expensive.

I found the Chilton manuals to be most useful as entertaining bathroom reading.

 

A couple more troubleshooting questions:

Do the instrument panel lights vary on the radio faceplate when adjusting them?
Are all the instruments brightly illuminated when the switch is positioned in Parade Mode - position just before the interior lights are activated?
Has any work been done under/behind dash before the issue began?

Since you subbed in the replacement radio with no change in symptoms two assumptions can be made, it's not the radio or the new radio has same symptoms. Chances are it's not the radio. On to power (fuses) and grounds (interest piqued due to the front-end accident) ...and mystery stuff. Start simple and work to toward total insanity and confusion.

 

OK. Doing some research, I will assume your Gen 2 is a 1999. (Posts on your Profile page).
I dug out a 1998 FSM and compared it to the 2002. No significant difference other than a Halo Light at the ignition switch and a MUX connection. (I guess you do not have steering wheel controls for radio volume, band and station changes?)
When the radio was swapped out there should have been two rectangular connectors plugged into the back of the radio and one single wire (IIRC) gray in color attached to a case ground tab on the case/housing of the radio. That is a very important radio ground connection. Were all three securely connected?
Most fuses involved with the associated radio circuits would affect other circuits if they were bad. Two fuses may be discrete to the radio. However, they don't address both reported issues individually. This is where connections/connectors, especially grounds come into play.
Fuse 4 - Junction Block - I don't think it would relate to the fluorescent display being inop though
Fuse 8 - Junction Block - Fused Ignition Run-Acc for radio.
G-100 Left forward fender well shield - under hood - engine compartment - near windshield washer bottle - look for clean solid connections and loose disconnected wires in the area.
With the radio connected and exposed to access the metal case, check the radio case to a metal ground point anywhere away from the radio with an ohmmeter. Should have less than a couple ohms. This may indicate no ground issue. The accident makes the under hood area highly viable for an issue.
Connector C-203 Under dash - ensure it's properly engaged.
Connector C-134 Under dash - ensure it's properly engaged.

A start...

 

Brucejohnson and Matt42, thank you for all your input - you both have given me a ton to chew on, more than I’ve found anywhere else!

About the accident which was somewhere around 15 years ago, the only issue with the radio was the display going dark, but all other functions remained viable, tuning/searching, volume, amp switches, speaker toggle, setting stations. Never used the cd/tape players but don’t know on that.

Swapping the replacement radio in, display works, haven’t noticed any difference in lighting using various functions but will investigate.

Brucejohnson, you wrote:

The radio supplies the voltage to activate the Radio Choke Relay which is grounded at G100, located at left front fender area under the hood near the windshield washer fluid bottle. If that ground were bad several other items could be affected like the heater fan. Something to check to see if a ground wire got disconnected/damaged during your accident repair

Interesting that you mentioned this particular ground. It is in fact problematic. Not sure if it was damaged in the accident but for years I’d been chasing a transmission hunting issue and would periodically clean yhe grounds. This nut was frozen and when I tried to undo it the bolt began tearing the fender metal, so I stopped. Stupid of me not to try some PB Blaster first. It’s been his way for years, though. I just tested voltage between the nut and positive battery terminal and got mV’s, not 12+ so there’s a problem. Not sure if this is a change between before the speakers quit working or after, but your mentioning it is interesting.

A mechanic husband of a friend had mentioned creating a new ground to try to solve the transmission hunting issue (which has improved each time I’ve gotten new batteries). He’s not cheap. How easy would it be to relocate this ground and how much time might something like that take?

I should add that I’m a she not a he, and while I have worked on this truck myself over the years for a variety of issues, electrical and metal tapping are not areas I’m comfortable with!

 

That part I was aware of when you first started posting, by looking at your profile and icon. That's great in my book. Nothing wrong with that and enjoying the truck while twisting wrenches to get to know it intimately.
Back in the late 60's my ex-fiancé (the one I did not marry ) would jump right in when I was modifying and fixing vehicles. She learned a lot and wasn't afraid of grease or having body parts being cut, spindled and/or mutilated, while gently and judiciously applying an occasional, properly applied yet "mostly polite" verbal selections like "pigdog" or when really serious, a louder "Schwein Hund" for encouragement to those parts failing to align properly.
A bubbly champaign bottle opening she WAS NOT. More like a well shaken warm Deutches Bier, sooo many fun bubbles!

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With this update it sounds like the now working display was radio related and the front speakers and tweeters are still quiet. A BL/VT (Black/Violet-striped) wire attached to G-100 supplies the ground for the Radio Choke Relay. If that wire is broken or the ground compromised the relay will not energize.

Check Fuse 4. It supplies the voltage to the front speaker/tweeter amplifiers.

The bold items, with associated wires, splices and connectors are the areas of concern for the remaining discrepancy, inop ft speakers/tweeters.

 

@Reluctant Mechanic, A better choice on those stuck ground nuts would be Fluid Film. I know Auto Zone carries it. It helps stop the corrosion from happening along with helping to loosen it. I also think it's great that you're willing to work on your truck. The ground relocation could be as easy as using a self tapping screw. Screw it in, back out and apply a rust protector like Fluid Film in hole, add the ground wire and thread back in.
For the electrical work, a simple digital volt meter is your friend! Learn how to measure Ohms and the such. Wire tracing is something that I don't like and I'm very familiar with wiring. Have many meters, and a tracer and hound, and also a Power Probe. Just ask the questions, and I'm sure someone will chime in with help. Understanding that wire are solid and with tracers can help locate them in other connectors. Good luck and don't worry about whether you're a gal or not!

 

You're very welcome! We all share what we know to help each other in a time of need. TDR is a great site for sure! OK, the best site!

A weak battery condition sure has strange effects on the hidden intricacies with the Gen 2 trucks. Both my previous 98.5 and 02 had strange issues, which included transmission shift anomalies even though there were no other "apparent" issues. My go to mechanic said change the batteries. Gee. It even turned over quicker and with more power, the other "perceived" issues disappeared, too. Interesting...

As far as the ground G-100 wanting to be stubborn...
When taking a continuity or voltage reading you may need to "dig/penetrate" through the rust, corrosion, paint of the terminal to get an accurate reading.
Sounds like yours may be loosening up. I have forgotten, is the stud bolt pressed/crimped in, welded, or bolt and nut? Nothing in the FSM to address the location...or I've looked too hard and overlooked it.
You should be able to clean and repair the existing stud, or if it is not repairable, make your own new and improved stud by using the existing hole, or drill a new hole in a location to where all the ground wires can easily reach. Clean the paint from around the hole, get proper sized bolt and install a star washer* on the head, insert into the hole, add a star washer* then nut to make a secure stud post for the ground terminals. Inspect the ground terminals and clean or repair if needed. Place the terminals on the new stud and secure with proper washers and nut. A little protection coating added, paint or special coating will help for the long run.
Keep us posted with your progress.
We're all here to share and assist.

*A star washer digs into the metal to make a more positive connection through light surface corrosion and other contaminates to the surrounding metal as well as inhibiting any fastener loosening through the heat and vibration cycles. Corrosion protection advised.

 

I wonder if you'd be able to get good enough contact with using a rivet-nut as the anchor? I've had so so success with continuity. Most of the rivet-nuts I've worked with are aluminum and not steel. I would think with a flange steel rivet-nut being used with cleaning the side before placing in the hole would help a lot! As @brucejohnson has stated, a good ground may solve the issues. These trucks are very temperamental about their grounds! Every time something starts to go sideways with my truck, 1st; check battery voltage and cranking voltage, 2; look for any loose or broken grounds. Keep hunting for the problem and TDR members will help as needed!