Cable Modem Troubleshooting: RCA DCM315

Light patterns, images, manuals and more helpful info for the RCA DCM315 cable modem –

Manufacturer: RCA Model: DCM315
Modem Light Indicators (during normal operation)

Flashes when you have unread email messages (only when supported
by the ISP).

Cable Activity

Off – No traffic is passing through the cable modem.
Flashing – Indicates traffic passing through the cable modem.

Cable Link

Off or Flashing – Modem is not acquired.
On – When both this light and the "Internet" light is on steady,
the modem is acquired.

PC Link

Off – No connection to the PC is detected or the modem is in
standby mode.
Flashing – Indicates activity between the modem and PC.
On – The connection to the PC is detected.


Off or Flashing – Modem is not acquired.
On – When both this light and the "Cable Link" light is on steady,
the modem is acquired.

Notes and Useful Information:

When the modem is turned on for the first time (and each time the modem is reconnected to power), the modem lights flash in a pattern that enables you to recognize at which phase of initialization the modem is in. The pattern begins (from right to left):

  1. Internet Light blinking alone – Modem is searching for downstream signal.
  2. Internet and PC Link blinking together – Dowstream is tuned and searching for Upstream signal.
  3. Internet, PC Link, and Cable Link blinking together – Upstream is tuned and receiving IP address.
  4. Internet, PC Link, Cable Link, and Cable Activity blinking together – Downloading configuration file.
  5. All lights blinking together – Registration in progress.

Installation and User Manual

Manufacturer Product Website


5 thoughts on “Cable Modem Troubleshooting: RCA DCM315”

  1. Pingback: Simplehelp » Cable Modem Index

  2. Bruce Morrison

    I have a rca315 moden, furnished by comcast, which will not work no mater what trouble shooting tips I follow…………I’ve tried them all………several times but the only light that will stay lit is the internet light. So far comcast is about as much help as a buckett of rocks. I believe it is their problem because of the service agreement with them but in the meantime is there a solution I haven’t tried or do modems just simply give out over time which is certainly understandable?

    Thank you for ANY comments you may have.
    Bruce Morrison

  3. Bruce,

    My husband and I have had the same problem with comcast modems. The first one we had kept messing with the connection, so I went in today and traded it for a “New” one… the RCADCM315. It connected to my computer just fine, but he had some problems with his again. Comcast gave us the same “Well, we don’t supply drivers, only the connection” (stupid but true)

    The absolute ONLY way he can get internet is to have both the USB AND the Ethernet plugged in at the same time. Not one, not the other, but BOTH. It’s pretty retarded, but it works. Try plugging both in, and if it doesn’t immediately fix it unplug the box, wait 10 seconds, plug it back in, and restart your computer.

    Good Luck!

  4. Hey everyone! So of recent, I’ve been having an issue involving my RCA modem. I’m sure it’s probably an easy one to figure out, but with classes starting tomorrow and me getting prepared, I do not have the time to solve this mystery. Well anyway, I have an RCA modem, and it appears that random times, the cable activity & cable link loses connection and it stops lighting as well, leaving only my PC link and Internet light of course. The modem is hooked up to the basement, and the wire runs through the ceiling unto the first floor, where the cable box also is located. Now, I think maybe I should probably check on the cable splitter since the cable does divide into a splitter, which therefore makes three extra cable wire thingys that goes into the basement, the living room, and the other bedroom. There doesn’t appear to be a loose wiring especially [unless of course there’s a vindictive force unscrewing and screwing it back on, which seems to be a likely irrational scenario]. But anyway, I will look more into the matter tomorrow. But I figure, with all the suggestions and tips and what not, I have an idea to go by. I have done google searching of course and troubleshooting, I don’t feel like talking to a guy with a thick accent named Steve on the phone either. Well, wish me luck, friends :D


  5. This modem has been the best I’ve tried in my 10+ years of experience. When I had a modem installed in a different location (city), they used a rinky-dink garbage “modem”. It literally would not work for more than 5 minutes at a time. I had the DCM315 in my apartment stored away from a prior install several years later. When I showed it to the Cable guys during the first time they were here installing it, I told them I’ve had years of reliable service with the model, they scoffed and said something like, “that’s old”. Basically it costs more than that junk they brought to install and here in NYC (in an ironically uber-expensive city) which is a city where every institution pinches every penny as hard as they can. I wasn’t surprised they tried to install some toy-ish garbage.

    So! After a day of experiencing my 5-minute intervals with the junk modem, I called the Co. and told them to install the REAL-DEAL that they used to use. Fortunately they consented, came and installed it. Worked immediately! Been ticking 8+ years.

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