flashing OD light on automatic GT

[killrb]

Anyone know what's going on here? A couple times I have had my 2008 GT start bucking and running weird right as the "OD" (over drive) light on the dash would flash repeatedly. I usually click OD off when I get off the freeway and onto my 45 mph side streets. This has been when it happened each time. The car runs awful until I stopped, shut the car off, then restarted.

Only done this twice, but I have no idea why. Brenspeed did my tune and they do not believe there can be anything in their set up causing that. Probably something for Ford to look at, but I can't get it to repeat.

Suggestions?

Brandon

 

[Torch Red GT]

it could be the cams, alot of people with cams have had that same problem.

 

[retfr8flyr]

The overdrive light will flash in different sequences depending on the failure sensed. Take it to the Ford dealer and they can read the failure code.


Earl

 

[Shades]

Could be that wing causing problems...


I kid. Any check engine lights? I'm assuming your tuned so see if you can use your handheld tuner and pull a code.


Also make try cleaning your throttle body, could be something simple like that, probably something clogged or malfunctioning, don't really see it being a tune issue at least not the way your describing it.

 

[SirKnightTG]

What cams do you have? I see your sig says comp but are they a rough idling set of comps?

Rough idling cams will cause flashing O/D light issues with the auto causing it to shift weird. Some know how to tune it out. I'm having this issue with my hot rod cams. Luckily Doug @ Bama knows how to tune it out and I have one of his tunes, but my Brenspeed tune and my BBR tune do it. I'm afraid the "fix" in the tune is just covering up the real issue though.

Also, for me and everyone else pretty much, this only happens under heavy stop and go traffic (where the brake is used a lot) and doesn't matter if I have the O/D turned on or off.

One other guy who has this issue too said he got a P0745 code. This seems to somewhat jive with what Brenspeed told me the flashing O/D light usually means.

I've been trying to figure this out, and I'm really thinking it's a vacuum issue due to these lumpy cams giving you lower vacuum. And since it happens only in heavy stop and go traffic where you use the brake a lot (and brakes use your vacuum), it kind of makes sense. Another guy said this issue is less and less likely to happen if you run a high idle as opposed to a low idle we normally like to run w/ rough cams. So this really sounds like a vacuum issue to me and somehow, a too low of a vacuum is causing something funny to happen where the line pressure solenoid is seeing a lower than normal voltage, thus throwing P0745. Maybe I'm wrong about all this but it sure seems likely to me. I'm going to be doing more tests to see if this is true or not (I'd be pretty surprised if not).

Of course, your issue may be something else. But I do know now that rough cams + 5r55s = issues and it's common.

I've been working with Justin Burcham of JPC on this issue. I haven't heard back since my last email to him but I'm sure he'll figure out something.

 

[SirKnightTG]

I I'm assuming your tuned so see if you can use your handheld tuner and pull a code..

The SCT is not going to pull trans codes and that is what's being set.

Ford, many car parts places and many shops should be able to read a trans code.

 

[redstangs9308gt]

I just wanted to say that I am upset with Brenspeeds email tunes. Their N/A tunes was great for my situation but they droped the ball on my F/I tunes.

 

[Shades]

The SCT is not going to pull trans codes and that is what's being set.

Ford, many car parts places and many shops should be able to read a trans code.

That's what I meant if he was pulling engine codes as well as the flashing O/D light. Ty for clearing it up though.

 

[MexGT]

My car O/D light flashes also, but in my case, its because my solenoid is taking a shit and therefore my whole trans is going bye bye.

 

[Charlie Sheen]

...for me and everyone else pretty much, this only happens under heavy stop and go traffic...

That was my case as well. Sad part is that the OD light was not blinking before I destroyed EITHER of the transmissions I've replaced.

 

[Shades]

That was my case as well. Sad part is that the OD light was not blinking before I destroyed EITHER of the transmissions I've replaced.

Don't you like surprises in your life?

 

[one.wicked.stang]

Wes@TPS can fix that problem right away, did for me. In fact I think he may have been the originator of the fix. Tuners do talk to each other.

 

[Vashthe3rd]

drive again, if it happens try and drive it to someone who can take care of it like Ford.

Then again maybe it's your car telling you it hates its own life......
I'm not kidding.

 

[killrb]

Then again maybe it's your car telling you it hates its own life......
I'm not kidding.

Excuse me.... but what do you mean by that?

To everyone else (pretty much anyway) thanks for the help.

Brandon

 

[2mchtoy]

so true

My car O/D light flashes also, but in my case, its because my solenoid is taking a shit and therefore my whole trans is going bye bye.

yup, same thing happened to me, once the light starts to flash, I got a solenoid code on my predator and then not long after that I lost 3rd gear. I bought another tranny and am hoping that they come out with some performance internals for the 5r55s before the other dies, I don't look for it to last too long at over 600rwhp.

 

[killrb]

yup, same thing happened to me, once the light starts to flash, I got a solenoid code on my predator and then not long after that I lost 3rd gear. I bought another tranny and am hoping that they come out with some performance internals for the 5r55s before the other dies, I don't look for it to last too long at over 600rwhp.

UHG!!! That doesn't sound good at all! A friend of mine is suppose to bring his scanner over Friday so we can figure out what codes were tossed out. I don't have the rough idle cams and this doesn't happen in stop and go traffic like some other guys mentioned. Crossing my fingers it's something simple. Will contact Brenspeed again too just to double check with them based off some other info you guys posted on here.

Hope I'm not buying a new trans anytime soon!!!

Thanks,
Brandon

 

[SirKnightTG]

Well if it's not from having rough idling cams (which is fixable in the tune thanks to Wes@TPS) then this may be a more serious issue.

My issue is not serious, just annoying and is the direct result of too low of vacuum from the hot rods...I think.

Damn you auto!

 

[SirKnightTG]

yup, same thing happened to me, once the light starts to flash, I got a solenoid code on my predator and then not long after that I lost 3rd gear. I bought another tranny and am hoping that they come out with some performance internals for the 5r55s before the other dies, I don't look for it to last too long at over 600rwhp.

I've heard good things about level 10's 5r55s.

 

[MexGT]

ok so in few words, we autos can get the O/D light flashing once we have "big" cams due to lack of vacuum ?

 

[SirKnightTG]

Yes. The trans is getting a signal based off the vacuum (from the some sensor I assume) that after a lot of braking, taxing the lower vacuum even more making it seem like the engine is barely running, and makes the line pressure solenoid not do the right thing. It appears this causes too low of line pressure which puts the trans in a failsafe where it will not upshift until past 3K to help build up more pressure to avoid slipping.

It's not a problem as long as you don't use your brakes a lot. That taxes what small vacuum higher duration cams give you to the point that it gets too low.

I still wonder if a vacuum can would help this any. Then the question is, WTF do you install it? lol.