Do the following test:

1. Unplug the brown electrical connector at the brake switch. Jump the terminal cavity with the White/Yellow wire to terminal cavity with White/Blk wire.
2. At Connector C554, test whether there is voltage at terminal no. 7 (that is where the White/Blk wire is.
3. If there is voltage at terminal no. 7 at Connector 554, individually disconnect the connectors for the brake lights. Measure the voltage at each connector's Wht/Blk wire. -- Is power getting through?

 

redbull-1...continued thanks for your guidance. Hope you had a good thanksgiving. Sorry for delayed responses....I'm struggling with a bout of diverticulitis right now. So I did the check for voltage at terminal 7 and got a "0" voltage. Then I made myself a long lead from the positive terminal. When I put the battery voltage on the different leads (shown) on the male side of C554 I can light all the different rear lights. So the backend harness appears to be good. Is there any chance a relay has failed?

Thanks again,
Mark

 

It would not be due to a relay.

Since you have power (+) at the Wht/Yel wire cavity terminal no.2 at the brake light pedal position switch harness connector and no power at terminal no. 7 of Connector C554, there is an open (break) in the circuit.

Now check the following for the open (break):

1. Again, unplug the brown electrical connector at the brake switch. Jump the terminal cavity with the White/Yellow wire to terminal cavity with White/Blk wire.

2. On the driver's side under-dash fuse box, check for power (+) at terminal number 20 (Wht/Blk wire) at Connector O (front of fuse box). If there is power there, move on to next check.

3. On the driver's side under-dash fuse box, check for power (+) at terminal number 5 (Wht/Blk wire) at Connector B (back of fuse box).

To check for power at Connector B, you may want to backprobe the terminal. Backprobing is either using a backprobe set or using a thin needle or something and making contact with the metal terminal of the connector without piercing the wire in the back of the still connected connector. Care must be taken to ensure that the wiring does not get damaged. You can use something like a T pin, available at Walmrt, etc., and backprobe. These pictures are just to give a picture of the concept of backprobing without piercing any wires.

https://www.hondaaccordforum.com/foru...%5D-t-pins-jpg

https://www.hondaaccordforum.com/foru...back-probe-jpg

Terminal numbering for female cavities terminals are on the wire side. Terminal numbering for male terminals are on the cavity side.

 

Use you long lead with and supply power to the wht/blk wire at the brake pedal switch (unplugged) with everything else plugged back in. Do your brake lights turn on?

 

red bull-1, I got some time to spend on this tonight. First to make sure I knew where I was, I redid some of the previous work. Since I haven't used a DVM to any extent before, I always make sure I can read volts across the terminals, and double check to make sure I have found a good ground wherever I'm working. This reduces the chance of operator (me) error. To summarize...
* I have 11.82v at terminal #2 on brake switch (white yellow)
* I jump #2 and #3 (as illustrated previously) and do NOT get brake lights
* I check #3 on bake switch terminal and do NOT get a ground. (I connected the black DVM lead to the common ground under the dash and touched the red to #3 - no continuity beep.)
* I ran positive form the battery post using long lead to the trunk and can turn on combinations of tail lights by touching various terminals on the male (trunk harness) side of C554.
* I checked fuse #47 under hood and it looks and tests (continuity with DVM) good.

... One side note - when I check my battery across the posts, it tests around 11.8v. I have seen that some places say that this is in reality a dead battery. But I can start and drive it with no problem. Can this be the issue?

... so having done the above, I launched into your instructions. I made a big picture to help discussion...
The first thing I discover, when looking at connector O under the dash is that there a appears to be a wedge of wood driven into the back of it. See the lower left picture with the single arrow. Either someone has been up to some mischief, or maybe somebody used this as an insertion/extraction tool? Upon pulling the wood piece out, it seems like the whole connector is loose. I pushed it back in with my fingers and it seemed to seat OK. So then I went ahead pulled it out and checked the voltage in all the cavities. The upper left picture shows what I got. I am not sure if I got the numbering right, but it looks like #20 does in fact have about 12 (a little less, more like 11.7) volts.

Next I went for your second check. (Picture on right.) If I have the numbering right, #5 has 0v. It has a thicker white/black wire. I checked the others on that side, and the one above it, #4 with a thinner yellow/green wire, has about 11.7 v. None of the others show any volts.

So is this telling me I have an open lead in the fuse box on that side?

Thanks as always for your help!

markb

Piece of wood!

Close up ...

 

1. The voltage measurement at the car battery terminals of ~11.82 would not be the cause for the open in the brake lights circuit.

That voltage would normally be a concern regarding starting and normal operation of the car; but, you're able to start it and drive it fine. You may want to re-check yourself.

2. Connector B has to be plugged into the fuse box, when you are measuring the voltage at terminal no. 5. Are you back-probing the terminal?

Yes, if there is power at terminal no. 20 of Connector O and no power at terminal no. 5 of Connector B with both connectors plugged into the fuse box, there is an open. If that is the case, the loose connection at Connector O maybe the cause or an open in the fuse box. Also examine the condition of the metal terminals on the fuse box where Connector O plugs into.

3. Locate Connector K and measure for voltage at terminal no. 7 (see attached images) by back-probing.

4. It is up to you; but, it is confirmed there is an open, you can always splice a piece of wire between the White/Black wire at terminal no. 20 of Connector O to terminal no. 5 of Connector B.

 

You verified that the wiring from the trunk to the brake lights work.

You haven't verified the wire from the brake switch to the trunk connector is working.

Supply power to the wht/blk wire at the brake pedal switch (unplugged) with everything else plugged back in. Do your brake lights turn on?

The 11.8V measurement at the wht/yel wire at the brake switch can mislead you to thinking you have proper voltage when current is flowing through the circuit. A partially damaged wire can have a large drop in voltage when current is flowing through it, while the same wire it will show 11.8 volts with no current.

 

.......... tried it, PAhonda, but no lights. Thanks!

 

That voltage would normally be a concern regarding starting and normal operation of the car; but, you're able to start it and drive it fine. You may want to re-check yourself.

Understood.....I have checked it a number of times with the same output.

Yes, if there is power at terminal no. 20 of Connector O and no power at terminal no. 5 of Connector B with both connectors plugged into the fuse box, there is an open. If that is the case, the loose connection at Connector O maybe the cause or an open in the fuse box. Also examine the condition of the metal terminals on the fuse box where Connector O plugs into.

I looked at the metal connectors with the aid of a mirror and they look OK. But in the process (this is a real contortionists job!) I discovered that the clip for connector O is broken - that explains the wooden wedge in the connector. Without that it is pretty loose, actually. I'll need to get that tighter somehow. And I did back-probe on connector B.

3. Locate Connector K and measure for voltage at terminal no. 7 (see attached images) by back-probing.

I did that....here is a picture of my T stuck into what I hope is the correct cavity. I had a goofy little cheap endoscope thing and hooked it to a laptop to get a picture. I had a heck of a time getting in there. Used a needle nose plier to plug it in there, and was able to push it in with my finger. When I check it with the brake switch plug lumped there is ) voltage - nothing. I pushed it in again and checked a couple of times.

4. It is up to you; but, it is confirmed there is an open, you can always splice a piece of wire between the White/Black wire at terminal no. 20 of Connector O to terminal no. 5 of Connector B.

Do I need to leave those wires plugged in, or can I pull them out and connect them, with electrical tape to prevent a short?

Also, is the alternative to splicing to replace that fuse box?

As always, thanks for taking your tie to help me out!

markb

 

Why are you testing up by the fuse box?

The brake lights work by supplying power on the connectors in/near the trunk. The brake lights don't work when supplying power at the wht/blk wire at the brake pedal switch (as long as the power source is external by running from the + batter post. This has to be a damaged wht/blk wire somewhere between the brake switch and the trunk.