Driving with four way flashers

[Ted Lambert]

Originally Posted by KSCRUDE

This is a hard pill to swallow. But I've been in the trucking business for over forty years, and I never run the four ways unless its a emergency. But I do run the tail lights most of the time, and DRLs all the time. If they can't see that, they are going to run over you anyway. I don't think the flashers are related to the transmission in any fashion.

In Alberta I am not sure if it is a law or not but. All the rigs are using them pulling up steep grades. All our drivers are doing it.

[subford]

Originally Posted by subford

What year are you speaking of?
The F53 with the E4OD TC clutch (1989-1997) is operated by grounding a wire by the PCM Computer. The other side of the solenoid is a common power supply to a lot of devices. The Computer has no way of knowing the four way flashers are on.

I think this would also apply to a few years after that with 4R100.

I will say I was wrong in this post.
The computer will look at the BOO switch output and the Hazard Flashers will back feed to the BOO switch and this would be the same as pushing on the brake peddle. The speed control also looks at the BOO switch and will turn off if the Hazard Flashers are on.

This has nothing to do with the brake lamps so the turn signal lamps will not turn off the speed control and unlock the TC.
The computer does not know if the brake/turn lamps are on or not as it has no input from the lamp circuit.

QUOTE:
Posted by Mark Kovalsky
Yeah, I do know about this.

It's true. The four way flashers will cycle the torque converter clutch. It wasn't intentionally designed that way, it was an oversight.

The PCM unlocks the torque converter when the brakes are applied. The PCM looks at the brake light circuit to determine when the brakes are applied. The PCM can't tell the difference between the brake lights and the four ways, in the circuit they look identical.

There was a fix put in, but I can't remember exectly when. I thought it was around '97, but that's too long ago for my limited memory. The fix was to calibrate the PCM to ignore the brake light circuit if the go pedal is more than 10%.

__________________
Mark

Former Ford automatic transmission engineer, 1988-2007.

End of quote.

[BFlinn181]

I read the whole post at Plowsite.com and there seems to still be a bunch of questions. Only the OP of that 'Warning' and the person claiming to be an "ex Ford Trannie Guy" report it is a real issue. In a transmission used in hundreds of thousands of trucks, from f-150 on up for many years, why wouldn't more people be aware of this?

Doing a number of Google searches for this problem, it only appears at the Plowsite.com link. AND NO OTHERS.

I'm not an expert on Ford F-53 motorhome chassis, how many only have the 4 speed over drive transmission? The newer models with 5 speed tow/haul aren't included.

As some of the skeptics on Plowsite mentioned, if the brake light switch triggered the transmission lockup clutch and the cruise control, why wouldn't people notice the surging of the lockup clutch or cruise control going off? Why isn't this a more widely known issue? I'm still a skeptic.

[terry735001]

GM is not any better

now that i have all most rewired MY hole RV... 8.1L / allison
they splice off so many times for the ground and key on power its not funny and run most of the motor on 2 fuse only

i have pulled it apart and now run alot more then the 2

[NeilV]

So the bottom line was posted by a person reported to be a Ford Design Engineer which seems to indicate that this was resolved with an flash back in 97 which should have been applied anytime the vehicle with that specific E4OD transmission was brought in to a Ford Dealer for service so if you have an E4OD transmission that still does this you may be able to resolve it by having the flash loaded. Pesonally I would only have the 4 way flashers on if I was stopped or unable to maintain 45 mph due to a grade and had already dropped out of overdrive so if I had a early to mid 90's E4OD equipped F53 this would be a non-issue for me. Plowing snow I would not be in overdrive and again this would not be an issue especially since I probably would not be plowing snow with an automatic transmisson anyway. Personally I ran old time W200 E20 Special Power Wagons with 383 or 440 engines, New Process manual transmissions, locking transfer cases, posi in the back and limited slip in the front drive axles with 478 gearing for plowing snow.

"Posted by Mark Kovalsky
Yeah, I do know about this.

It's true. The four way flashers will cycle the torque converter clutch. It wasn't intentionally designed that way, it was an oversight.

The PCM unlocks the torque converter when the brakes are applied. The PCM looks at the brake light circuit to determine when the brakes are applied. The PCM can't tell the difference between the brake lights and the four ways, in the circuit they look identical.

There was a fix put in, but I can't remember exectly when. I thought it was around '97, but that's too long ago for my limited memory. The fix was to calibrate the PCM to ignore the brake light circuit if the go pedal is more than 10%.

__________________
Mark

Former Ford automatic transmission engineer, 1988-2007."

[Murf2u]

Corrosion in the trailer plug socket will do the same thing. The corrosion forms a partial short circuit and power from the running lights or aux. power can back feed the brake light circuit causing the converter to think the brakes are being applied and to unlock.

[hydro45640]

If you look at the owners manual you will find that they are called "emergency flashers".

[Ted Lambert]

Originally Posted by BFlinn181

I read the whole post at Plowsite.com and there seems to still be a bunch of questions. Only the OP of that 'Warning' and the person claiming to be an "ex Ford Trannie Guy" report it is a real issue. In a transmission used in hundreds of thousands of trucks, from f-150 on up for many years, why wouldn't more people be aware of this?

Doing a number of Google searches for this problem, it only appears at the Plowsite.com link. AND NO OTHERS.

I'm not an expert on Ford F-53 motorhome chassis, how many only have the 4 speed over drive transmission? The newer models with 5 speed tow/haul aren't included.

As some of the skeptics on Plowsite mentioned, if the brake light switch triggered the transmission lockup clutch and the cruise control, why wouldn't people notice the surging of the lockup clutch or cruise control going off? Why isn't this a more widely known issue? I'm still a skeptic.

I have done a GOOGLE search for the fellow claiming to be a Ford Transmission Engineer. Try that for yourself I was quite impressed by what I found. There are lots of references by him concerning transmissions.

In your mind are you suggesting anybody on this site who says he is a Engineer mechanic or Rocket Scientist is a fraud? I don't believe you feel that way.Here is a link that might interest you.
http://powerstrokenation.com/forums/...ead.php?t=4338

[subford]

By the way there is no item in the MH called the Brake Light switch.
It is a BOO switch and does a lot more than turn on Brake Lamps.
The BOO switch circuit has an output through the Multi-Function Switch to Brake lamps if the Multi-Function Switch is not set to left or right turn position. Then it only outputs to the not selected side.
This is why when you turn on the turn lamps the TC clutch does not drop out.

The outputs from the Brake On/Off (BOO) Switch go to the:
1. Powertrain Control Module (PCM) Computer.
2. Speed Control Servo/Amplifier Assembly
3. Lone brake lamp circuit sometimes call the high brake light.
4. Shift Lock Actuator.
5. Accessory Feed.



/

[BFlinn181]

I also searched and found the former Ford guy. Impressive experience in Ford and GM transmissions, including a Ford patent for O/D switch in A/T. Also quite the entrepreneur in auto repair and birthday card businesses.

That being said, IF the reported issue by streetfrog on the Plowsite.com forum in 2008 seems to be a NON-issue there and anywhere else. If the use of federally mandated emergency flashers actually could damage the lockout clutch in the transmission was a REAL issue, why wouldn't it be wider known?

If I had an F-53 chassis or any other Ford truck I wouldn't hesitate to use the flashers when needed or required for safety. I bear you no ill will, and not accusing you of any wrong, narampa, I just question the supposed 'warning' since it doesn't seem to be an issue anywhere else.

[jamesrxx951]

Originally Posted by subford

By the way there is no item in the MH called the Brake Light switch.
It is a BOO switch and does a lot more than turn on Brake Lamps.
The BOO switch circuit has an output through the Multi-Function Switch to Brake lamps if the Multi-Function Switch is not set to left or right turn position. Then it only outputs to the not selected side.
This is why when you turn on the turn lamps the TC clutch does not drop out.

The outputs from the Brake On/Off (BOO) Switch go to the:
1. Powertrain Control Module (PCM) Computer.
2. Speed Control Servo/Amplifier Assembly
3. Lone brake lamp circuit sometimes call the high brake light.
4. Shift Lock Actuator.
5. Accessory Feed.



/

Have you ever noticed that your cruise control will kick out when you turn on your turn signals? following the circuit the turn signals and rear brake likes for most coachs are the same lights. I have never noticed any issues using turn signals in my old 93 motorhome. But I never drove with the 4 ways on either.

[subford]

The Speed Control (cruise) should not kick out when you use your turn signals as the Multi-Function Switch will open the path back to the BOO switch and its out puts. At the same time making a path to the brake/turn lamps from the flasher.
Or at least that is what the diagram says:


/

[jamesrxx951]

Originally Posted by subford

The Speed Control (cruise) should not kick out when you use your turn signals as the Multi-Function Switch will open the path back to the BOO switch and its out puts. At the same time making a path to the brake/turn lamps from the flasher.
Or at least that is what the diagram says:


/

I see what you mean and thanks for making me really look and study that diagram forever. If you have the second page to that diagram circuit 511 says it is for the brake lamps supplied by the body builder. So after correcting my self they cant use that circuit unless it is dedicated to brake lights only with no turn signals.

[subford]

The second page is in post #23 above.