Dashboard Parking Brake Warning Light Stays On

[MTMACK50]

Hello -  I posted last year about an issue with my 1991 Mack Midliner CS300-see the link here

Im hoping someone may have some knowledge on why the Parking Brake Warning Dash light stays on even when the Park Brake button is depressed and the wheels release.     Thanks Guys

[Vladislav]

If you haven't done any primary inspection I would point you out to the brake light switch wich might got stuck in "on" position.

Don't know where it could be located on Midliner and the most forum members seem like about that either.

So not much of help to your post.

 

I had the same issue with my R-model some while back. Found the switch being attached to the firewall. Actually you should look for a unit wich is attached to a air line and has a wire terminal (or two) on its body. Connecting/disconnecting the wires or wire to the ground (chassis) you can check it's what you're looking for or not.

Sure might be a short circuit in the stop light wiring and so on. 

In my case (to my big surprize) the trolley valve lever on the steering column was moved a bit from its off position and that initiated brake lights for all the time.

It was with no trailer either. But that how it was with a R-model, again, no practice with a CS.

 

P.S. If you google Renault Midliner electric scheme that could be the way to go.

 

Vlad 

[MTMACK50]

Thanks Vlad for your insight , I will work on getting the electric scheme to narrow down the options.

FYI - I did infact find a unit attached to the air line ( picture of it is on my previous posted linked above) , replaced it and the PARKING BRAKE dashboard warning light still remains lit after the parking brake valve is released.

 

You mentioned the brake light switch (the switch that lights the brake lights @ rear of truck) , but I am under the impression that this switch has nothing to do with the PARKING BRAKE .

The symptoms are that when the parking brake valve in the cab is released , the park brake "on" warning light on the dashboard stays lit , but the rear tail lights are not effected by this problem.

 

Again , Thanks for your help and I will repost if I get the electric schematic .

 

[41chevy]

Look  on or near the Parking Brake SKnob (button). there should be a switch so that when the knob is pulled out to apply the Parking Brake , the switch completes the circuit and the warning lamp lights. Probably only one wire in / one wire out. The switch could be dirty or just worn out. Where is the switch located on the Midliner ? Logically on or near the Parking Brake Knob.     Paul

[MTMACK50]

Hey Paul - See pictures attached - The parking brake air valve and the dash warning light that stays on.

The AIR powered Parking Brake knob is located between the two seats . The two air valves (parking brake and trailer air supply) come as one unit , I've removed this unit many years ago from its mounting place .. and I believe the only things connected to the knobs are the air lines.

- still searching online for a schematic of the parking brake system in this 1991 Midliner CS300

 

 

 

[41chevy]

Some where near the Knob or along the air lines has to be a brake light style switch  to light and shut off the warning light.  With out a wiring schematic the only alternative I see would be to follow the air lines from the P Brake Knob  and it should lead you to a switch unit.    Paul

[Challenger]

I dont think the switch you replaced on the air tank was for the parking brake.  Maybe it was a low air pressure sensor.   I would do what 41chevy says and follow the parking brake airlines, starting at the parking brake switch.  You'll find it.  

[Challenger]

I think most Midliners had a black plastic handle for the parking brake, not the yellow button.   Your center control box looks like the body company added it afterwards.  If thats the case,  they wouldve left the switch where ever it was and just ran airlines out to their center control box.  That would explain why the parking brake light switch isnt near the parking brake button/handle.   

[MTMACK50]

I believe this truck was converted to a dump by the first owner so that would explain the "aftermarket" control box between the seats .  

I will follow the lines from the valves and see what I find.

Any ideas what this switch looks like ?? Any generic pics I can refer to ?

Or , does the switch look like the one I replaced by the air tank? (pic shown in original thread @top of page)

Thanks for the FAST advice .

 

[41chevy]

Similar style I believe.    Paul

[MTMACK50]

So, I discovered an air leak from an approx 5/8" steel air line pipe that connects to one of the air tanks (drivers side) and runs behind the air tanks into the engine compartment which then connects to an approx 18" long steel braided hose . The pipe has many pinholes in it and the braided hose is badly rusted.  In my search fora new replacement pipe and braided hose has resulted in about $400 for the two parts and the pipe comes straight and I'll have to get it bent to match the one pictured below. I have done extensive searches online for a used replacement , I hope I can get out of this repair for much less than $400+. I was thinking of using ALL steel braided hose, Ive found a manufacturer online that deals in that type hose, but I need to get the correct fitting information which is metric. 

Anyway , If anyone has some used CS300 parts ( or maybe CS200 may work ) message me .

Thanx

[thomastractorsvc]

You cant use the DOT nylon air hose?

[Vladislav]

What's a problem with metric fittings? They're all over!! Sorry, couldn't resist myself

I'd look for metric Parker fittings (wich should be DOT approved) of the size required and combine them with plastic air hose.

And... I'm not sure Mack CS has original metric pipes marked DOT. If a part is metric it means it's origin is Renault. Renault might have different marks wich would be a mistery to DOT officer.

[MTMACK50]

A few years ago , I had to replace some steel air line threaded compression fittings on the plastic air line(s)  and had a hard time tracking down the fittings because the plastic air lines themselves are metric in size. This CS300 was made in France - says so on the vin plate.  

Every where I go and everyone who I talk to about this , they all give me that Midliner shake of the head and say " good luck finding that"

Look, Ive got one male fitting on the air tank , and one female swivel nut (just like on steel pipe in pictures) under the hood - I would LOVE to be able to convert off these two points and use a more widely available air line whether it be plastic or braided steel .

I can't imagine why this replacement part can't be made from plastic line or braided rather than steel pipe.

Ok so - Metric parker fittings that match each end of my rotted piece and then go from there. We'll see.

Thanks

[MTMACK50]

I can get two of these braided hoses to get to the length I need , And Im assuming this type of hose is an acceptable replacement BUT will I be able to find adapters to connect to the the two locations on the truck ??

 

[MTMACK50]

UPDATE -  ( for those Midliner owners and those who've helped out here )

Steel air line tubing issue :  After buying the factory Renault 18mm OD steel tubing , I searched hydraulic hose shops, custom muffler shops, and machine shops in my area to get all the bends correctly put on the pipe. No success. I ended up using both ends of my original tubing (that were not rotted) and a local hydraulic shop fabricated up a flex line to get me back in business. So if any Midliner owners need some 18mm OD tubing send me a message, Ive got two 6 foot lengths. FYI- alot of this tubing is used in the engine compartment as well on my CS300.

Air Park Brake Warning light constantly on dashboard - It's still on .

 

 

[Vladislav]

Glad to hear you have your air line issue resolved. I understand you wery well since I use to have exactly the same situation meeting a trouble with SAE pipes etc being in the completely metric environment. It's a bit easier here though because local "DOT" can't inspect such modifications knowing not what Mack truck is and wich styles of pipes it should have. And usually Renault either.

I'm afraid (and would advise) you should try to check in some Renault trucks or other European forums to get info on Midliner. Probably if you just don't say "Mack" talking about Midliner those guys might not find anything extraordinal in a request. Another thing that bothers me those folks might be found as French speaking community... Although if the memory serves Midliner was not a Renault (and Mack) product only. A shadow of Vulva was somewhere about that either. 

[Fraga]

Hi have the same problem but I'm my 2006 vision the P light stays on while driving any help what is causing this

Edited July 30, 2020 by Fraga