Radio Relay Function
 

My friend pointed out that I'm missing the radio relay.
I've been having no FM reception and couldn't figure it out. Cd player works and antenna goes up and down. Also AM works. Is this my problem?

Thanks
Yanni

I haven't checked the wiring diagram to verify, but I really don't think the missing relay is your problem.

The factory radio, and almost all aftermarket too, only have two power leads; a switched positive lead that powers the unit whenever the key is on, plus a constant 'hot' lead that only keeps the radio's internal memory alive.

Since you've stated that the AM radio and CD player are both functioning your system is still getting power. Although I've not read about the FD's stereo having a particular problem with broken solder joints (this is an issue with the tach), considering the stiff suspension that would be at least one possibility.

cool so how would I go about looking at the connections for the solder?

I can solder real well but will it be obvious like a hanging wire or what?
and is there a way to tell if I take the headunit out which wire is for the antenna?

What does the radio relay do then? It must do something lol?

thanks for your help
Yanni

I had great trouble finding the antenna wire. Finally I found it in a removable compartment near where the driver positions his left knee (mid lower leg). Remove the cover and there it was. The only strange thing is that I had to do a 2 male plugin cable to connect from there up to my player.

Reception came in fine afterwards. If do not find it and I have chance I can post a photo.

Vellj001, some factory radios use two antennas to avoid/minimize multipath distortion. Multipath can occur when the signal from one station gets bounced around between buildings, etc. so that it arrives at your antenna from two directions at the same time. Using a second antenna (usually just a wire in the windshield) and some intelligent electronics allows the radio to 'select' the strongest signal and ignore the weaker. This process goes on continuously so there is no noise from switching back and forth or delays in the sound. Therefore, missing the 2nd antenna might result in poorer reception and additional noise, but I think you’d still get some sound. If the main antenna was disconnected, who knows? I guess this could account for only AM working; AM is usually a stronger signal. T would sure worth checking before tearing in to the radio itself.

SurgeMonster, looking for broken solder joints is a PITA and most repairs generally end up being a 'resolder everything' type of solution. While there are ways to focus in on the more likely failure areas, without knowing the stereo’s insides and/or checking voltages, etc. it’s probably impossible to predict for a DIY approach.

If you can’t find any other cause and you’re comfortable attempting this type repair yourself, I'd start by opening up the radio's case so that you can see the bottom of the circuit card. Then starting at one corner, begin reordering each connection and progressing until all have been done. Be careful of applying too much heat, be sure to use a small diameter rosin-core type solder, and work slowly to avoid incorrectly bridging connections. The radio must NOT be powered at all while you do this work.

I bought a new stock headunit : )

I don't want to change the headunit because it looks awesome stock and blends with everything. I will try that out and if that doesnt work I'll be really confused lol

Yanni

i got an Alpine CDA-9835 and i love it because you can choose from 512 different colors for the buttons and i made it match my dash perfectly, someone asked if it came with the car... LOL, spectacular head unit

The radio relay is used ONLY with the Bose system to control the power to the additional amplifiers in the powered speakers, center ch and bass unit. IN non-Bose 93 models, this relay is absent and in its place is a jumper wire. (I assume that you're talking about the relay in the box at the front of the car.) This is all detailed on the Mazda schematic.

NO FM is likely a problem with the antenna feeders (coax cables from the antennas--there are 2) or the radio itself.

Speed thanks for the correct info!

I hope that it is the headunit because I don't feel like tracing the wires back. Its weird I had my car down for 6 months in the driveway for the upgrades and it just didn't work ever since.

Keep watching this thread please so maybe you can help me if the headunit doesnt fix it.

appreciate the help everyone
yanni