99 O/D Blinking...Trans flush or not??

[davkilb]

My explorer is running strong as it breaks into the 125xxx mile range...one thing that has always been an issue is my O/D light blinks. It wont start to blink until i go on the highway or other high speeds. What i think it is, is that its not shifting into overdrive. Sometimes it wont be an issue and will shift into overdrive and still start blinking. This issue is not new to me, ever since i bought the truck @ about 53xxx miles it's been turning on. When i turn the car off it stays off until i go on the highway or other high speeds. I brought it into a trans shop and they couldn't get a code. So i was wondering if anyone else has this problem, and also should i do a trans flush? Some say do it...some say don't??

 

[mp223]

If its already acting up, new fluid can't hurt. Don't do a "power flush", instead drop the pan, replace the filter and use two buckets to pump/replace the fluid already in the torque converter/lines.

 

[mp40]

Does the transmission shift hard with the O/D light on? My 1996 sport, (1999 4.0/5 speed auto swap) has been doing this lately.

It will sometimes start with the O/D light off, and while you drive it, the O/D light will turn on. Then, the transmission won't shift into 5th. This, and it shifts firmly first through 4th.

Sometimes, the O/D light will go out shifting smooths out and O/D returns.

This behavior isn't an issue (to me!) as it accelerates far better and shifts great.

I am wondering if I have a fuse out/sensor or something like that going on?

I would like to find out just what the problem is, so I can isolate the fault.

 

[FPGT24]

Does the transmission shift hard with the O/D light on? My 1996 sport, (1999 4.0/5 speed auto swap) has been doing this lately.

It will sometimes start with the O/D light off, and while you drive it, the O/D light will turn on. Then, the transmission won't shift into 5th. This, and it shifts firmly first through 4th.

Sometimes, the O/D light will go out shifting smooths out and O/D returns.

This behavior isn't an issue (to me!) as it accelerates far better and shifts great.

I am wondering if I have a fuse out/sensor or something like that going on?

I would like to find out just what the problem is, so I can isolate the fault.

my 99 XLT OHV V6 did that exact thing. never looked into it, sold it instead cuz the OHV didnt have enough power for me...going back to the SOHC...

 

[wood1]

A flashing light denotes the transmission has set a code doesn't it?

 

[ozmedia]

Yes and it's all on here

:JP:First of all you should scan it with a scanner that reads the Ford transmission codes. It sounds like a VERY common issue though.

It is likely due to TCC or EPC solenoid valves. They will cause too much converter slip and trigger the flashing o/d light and usually put it into limp home mode. It is also often due to a blown valve body separator plate gasket, which would be done at the same time anyway. They have since made the separator plate with a bonded gasket but it originally came with a two piece gasket and separator plate, which blew out. It was so common that Ford released a TSB on the issue. It also causes 2-3 shift flare, which is a quick identifier of the problem.

The 5R55e are also prone to solenoid and sticky valve issues (TCC, EPC etc), which are addressed best with the respective solenoid or valve body rebuild kits (sonax/transgo). It will provide more precise shifting when done too. You can do the separator gasket if you are fairly handy, patient and careful, but it is not usually time for a new transmission yet. You can also buy complete valve bodies online, that already have kits installed, and you'll have a practically new running trans for a few hundred bucks and a case of beer in your garage, more info in the links at the bottom.

As for flashing o/d light and the transmission clunking into gear, it is in Limp Home Mode (LHM) many Fords are programmed to do this as a precaution to help prevent further transmission damage and slipping. If you reset the system with a scanner or remove the negative battery cable for a few minutes, it will reset and go into normal shift mode again. As soon as the error triggers again, it will retun to LHM and the o/d light will flash.

Here's more VERY detailed info on the fix by the best Ford transmission guru's Glacier991 and BrooklynBay . These guys know more about Ford transmissions than anyone I ever met when working with Ford. If you can't follow thier step by step pictorials, you might want to have someone else do the work for you.

Brooklyn Bay's list of useful threads:
http://www.explorerforum.com/forums/showpost.php?p=1439158&postcount=17

Glacier's full rebuild diaries
5r55e rebuild diary: http://www.explorerforum.com/forums/showthread.php?t=14098

A4LD rebuild diary:
http://www.explorerforum.com/forums/showthread.php?t=137972

More info on your most likely problem:
http://www.explorerforum.com/forums/showthread.php?t=174202&highlight=2-3+flare

Just about any info you can possibly dream of is on here from Glacier991 or BrooklynBay. Happy hunting.

 

[mp40]

Thanks for the replies guys!

I had replaced the separator gasket in the transmission prior to this (in 2009) when I swapped in the engine/transmission. That, and I also replaced another valve in the valve body (I can't remember the exact valve name, just that it was an up graded valve intended to address the 2-3 shift flare issue. It did its job though)

I would like to replace the entire valve body etc with the upgraded Sonnax valve body assy if someone sells the complete assemblies that is. Any sources?

 

[FPGT24]

Does anyone know how to prevent these transmissions from failing? All the Explorers I've had have had trans problems. my 97 SOHC had a trans put in around 110k then another one around 180k and at 220k it was slipping into 5th gear and slamming down through gears when you came to a stop. My 98 SOHC's reverse band broke. And my 99 OHV's trans would act funny in 3rd gear sometimes and the O/D light would blink.

It would be a blessing from god if my next Explorer has no trans issues at all as long as i own it.

 

[windsors03cobra]

Get the V8 with the good V8 trans, just changed the fluid in mine today at 230k. 60k on the fluid, little sludge on the magent, clean fluid and the bottom of the pan was clean as a whistle. Original re-usable gasket BTW.

230k truck runs and drives like a dream. I've driven Explorers with half the miles that drive like junk compared to mine. Best vehicle I have ever owned and as far as I'm concerned one of the best Exploder models ever built.

 

[wood1]

Thanks for the replies guys!

I had replaced the separator gasket in the transmission prior to this (in 2009) when I swapped in the engine/transmission. That, and I also replaced another valve in the valve body (I can't remember the exact valve name, just that it was an up graded valve intended to address the 2-3 shift flare issue. It did its job though)

I would like to replace the entire valve body etc with the upgraded Sonnax valve body assy if someone sells the complete assemblies that is. Any sources?

Central Valve Bodies. They are well respected here.

 

[mp40]

Central Valve Bodies. They are well respected here.

Thanks!

 

[FPGT24]

Get the V8 with the good V8 trans, just changed the fluid in mine today at 230k. 60k on the fluid, little sludge on the magent, clean fluid and the bottom of the pan was clean as a whistle. Original re-usable gasket BTW.

230k truck runs and drives like a dream. I've driven Explorers with half the miles that drive like junk compared to mine. Best vehicle I have ever owned and as far as I'm concerned one of the best Exploder models ever built.

I see the V8 models with bad trans all the time...I dont like the V8 models unless its a 2wd.