07 with flickering lights/accessory delay relay - Ford Mustang Forum
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post #1 of 4 (permalink) Old 07-31-2017 Thread Starter
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Joined: Jul 2017
Location: Round Rock, TX
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07 with flickering lights/accessory delay relay

Hi everyone, I'm new to the forum today. Seeking some debug advice.

We bought my son his 2007 Mustang 6cyl back about 7 months ago. Been great until a few weeks ago he started seeing his headlights flicker off and on at night. Once I got to see it happen, I noticed the headlights and taillights along with several interior lights and a relay (accessory delay relay) under the glove box were all participating. Every once in a while he gets a warning about low brake fluid too (and of course the brake fluid level is perfect). We replaced the alternator first thinking the voltage regulator was going out. Then I cleaned the battery posts and terminals. No improvement, so I started my research. Found out about the SJB issue due to the water leak problem.

So last weekend I pulled out the SJB and tore it apart. I didn't see evidence of water damage to the PCB or connectors. However, there is a connector, what seems to be C210 on a diagram, that had some white residue and corrosion on one of the pins. So this tells me there was likely a leak at one point. I scraped off the corrosion and sprayed all connectors down with some Radio Shack precision electronics cleaner. Sure enough, about 3 minutes after starting it up, same problem again. Lastly, I pulled the headlight switch out and reseated those connectors. Still seeing the issue.

I'm wondering if anyone has some additional suggestions before I spend $$$ taking it in to the local dealer. Seems to fail mostly right after startup, so it almost has a temperature symptom to it. Do you think I'm on the right track suspecting the connectors down in the SJB area? What are the chances the computer itself is bad and needs to be replaced? Is there a way to test that?

Anyone know of a wiring diagram that can help? I've seen the map and dash lights, the accessory delay relay, headlights, and taillights all tied to this flickering issue, so I'm hoping to find a diagram to narrow this all down to one cable/connector. And then there's the mystery of the low brake fluid warning, which we only see when the flickering was real bad.

Any help is appreciated!!!

PS. In case it's interesting, I've owned many '66-67 mustangs. Most recently a '66 GT convertible that I mostly restored. I ended up having to sell it in 2000 or so when my son was born. Boy those were a lot easier to work on! That thing probably doubled in value since I sold it too.

Last edited by RKPascarella; 07-31-2017 at 06:41 PM. Reason: Formatting fixes
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post #2 of 4 (permalink) Old 08-01-2017
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I will offer this.........I would purchase a Power Probe.....

You really don't need the $400 model.......this one is about $100


Member: Never trust a person over 40 who drives a Chevy club
Flatheads ain't so bad!
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post #3 of 4 (permalink) Old 4 Weeks Ago Thread Starter
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Joined: Jul 2017
Location: Round Rock, TX
Posts: 2
I know this thread is quite old now, but I ran across it again and have resolved the issue. We ordered a brand new Smart Junction Box and had the local Ford dealership's service dept install it for us. It's been a few years now and we've had absolutely no trouble since. Problem solved! I hope this helps someone in the future that runs into similar issues.
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post #4 of 4 (permalink) Old 4 Weeks Ago
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Location: Fort Worth
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Thank you for posting your fix, most don't these days and it can be frustrating. glad your car is doing well

Lots of bolt on goodies...
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