Parking Brake

[Ineedatruck]

I have no power when I turn on the master stop? The packing brake will not pull up. Will will prevent it from getting power? No test lamps, nothing showing batteries are connected.

 

[Ronmar]

First off, what year and model truck is this?

Does master stop mean main ignition switch above the start button?

The park brake, and the whole brake system does not require electricity. What it does require is air pressure. If the park control wont pull up, it is probably because it is already up? When the tanks drain the park control pops up all by itself to the brakes on position. If it will push in(brakes released) and pops right back up you don't have any air in the system…

 

[Ineedatruck]

First off, what year and model truck is this?

Does master stop mean main ignition switch above the start button?

The park brake, and the whole brake system does not require electricity. What it does require is air pressure. If the park control wont pull up, it is probably because it is already up? When the tanks drain the park control pops up all by itself to the brakes on position. If it will push in(brakes released) and pops right back up you don't have any air in the system…

The truck is a 1997 M1081. Yes. It is the rocker switch above the start button. I starting using the trouble shooting manual 20-1. step E2.2 . Thanks for the information on the brake. Since there were no lights, I wondered if there was a safety switch. I have no lights on the dash.

Thanks.

 

[Ronmar]

Ok, thats an A0. first check I would do is measure the voltage at the test points on the left side of the power panel. You have a ground(X3) 12V(X2) and 24V(X1) test points and you should see battery voltage measured on X1 and X2 to X3 test points, minus about 1/2 volt as it passes thru diodes in the polarity protection device. If you dont have battery voltage at those test points, you have an issue in the supply or ground wiring back to the batteries.

if you have good voltage there, turn on the main switch and measure again. If the test point voltage is still good, you have an issue associated with the ignition relay K2 Or its control circuitry(12v X2 thru CB70 to relay K2).

if the test point voltage is no longer good when you turn on the main switch, you most likley have a bad connection back to the batteries. Unloaded a bad connection will pass full voltage but like a kink in a garden hose the voltage will fall off as soon as any current tries to flow thru the bad connection. Those usually occur at the polarity protection device between spare tire and air filter as those are out in the weather…

The A0 schematic in the manual can be hard to use. Here is a simplified one page diagram I drew for the ign/start wiring that may be a little easier to follow.

 

[Ineedatruck]

Ok, thats an A0. first check I would do is measure the voltage at the test points on the left side of the power panel. You have a ground(X3) 12V(X2) and 24V(X1) test points and you should see battery voltage measured on X1 and X2 to X3 test points, minus about 1/2 volt as it passes thru diodes in the polarity protection device. If you dont have battery voltage at those test points, you have an issue in the supply or ground wiring back to the batteries.

if you have good voltage there, turn on the main switch and measure again. If the test point voltage is still good, you have an issue associated with the ignition relay K2 Or its control circuitry(12v X2 thru CB70 to relay K2).

if the test point voltage is no longer good when you turn on the main switch, you most likley have a bad connection back to the batteries. Unloaded a bad connection will pass full voltage but like a kink in a garden hose the voltage will fall off as soon as any current tries to flow thru the bad connection. Those usually occur at the polarity protection device between spare tire and air filter as those are out in the weather…

The A0 schematic in the manual can be hard to use. Here is a simplified one page diagram I drew for the ign/start wiring that may be a little easier to follow.

View attachment 888738

Thank you. I have the correct voltages at x1 and x2 as you explained with the switch on and off. The K2 relay was bad. I replaced it and I am getting the lights etc and NN on the Allison display.
I am missing the K26 relay. I see it is in your diagram so I assume it is needed. Do you know the part numbers for the replacement and for any 12 volts and 24 volt relays?

thanks again.

 

[Ineedatruck]

Thank you. I have the correct voltages at x1 and x2 as you explained with the switch on and off. The K2 relay was bad. I replaced it and I am getting the lights etc and NN on the Allison display.
I am missing the K26 relay. I see it is in your diagram so I assume it is needed. Do you know the part numbers for the replacement and for any 12 volts and 24 volt relays?

thanks again.

I wanted to add this for anybody new who may see this. You can get 2 different relays to cover the 4 called out on the PDP cover. The 12 volt is Bosch part number 0332209152. The 24 volt is 0332209204.

 

[coachgeo]

I wanted to add this for anybody new who may see this. You can get 2 different relays to cover the 4 called out on the PDP cover. The 12 volt is Bosch part number 0332209152. The 24 volt is 0332209204.

clarity check- Since your post above could be also read as... one can get by with two relay's instead of four..... is what you are intending to suggest:

that 12v relay -Bosch part number 0332209152, can be used for replacement the 12v spots pointed out on PDP cover. For the 24v spots relay- Bosh 24 volt 0332209204 is the ticket.

 

[Ineedatruck]

clarity check- Since your post above could be also read as... one can get by with two relay's instead of four..... is what you are intending to suggest:

that 12v relay -Bosch part number 0332209152, can be used for replacement the 12v spots pointed out on PDP cover. For the 24v spots relay- Bosh 24 volt 0332209204 is the ticket.

Yes. Is this correct?

 

[coachgeo]

Yes. Is this correct?

Seems correct to me. Just saw that it could be read different and maybe cause confusion is all. They seem to work for you thus far right?

@Ronmar or anyone else.... would these be same relay's for A1's too?

 

[Ineedatruck]

Seems correct to me. Just saw that it could be read different and maybe cause confusion is all. They seem to work for you thus far right?

@Ronmar or anyone else.... would these be same relay's for A1's too?

Thanks. I want to also thank @Ronmar for pictures of the Bosch relays and part numbers.

 

[Ronmar]

Well the pics were initially posted by Spanky Bear I just screenshot them for future reference

On the A1, With the exception of K1 and K2, which are the large 24V bolt-in ignition relays under the power panel, the A1 with the circuit board power panel actually uses 12v coil relays for all the power panel plug in relays. If you look at the A1 schematic, on relays that are controlled by 24V, you will see a 82 Ohm resistor in series with the coil to knock down the current(and ultimately the voltage) to a level a 12v relay coil will accept long term without overheating.

The A1R with the Power Distribution Module boxes, appears to have returned to using both 12 and 24V coiled relays…

 

[coachgeo]

Well the pics were initially posted by Spanky Bear I just screenshot them for future reference

On the A1, With the exception of K1 and K2, which are the large 24V bolt-in ignition relays under the power panel, the A1 with the circuit board power panel actually uses 12v coil relays for all the power panel plug in relays. If you look at the A1 schematic, on relays that are controlled by 24V, you will see a 82 Ohm resistor in series with the coil to knock down the current(and ultimately the voltage) to a level a 12v relay coil will accept long term without overheating.

The A1R with the Power Distribution Module boxes, appears to have returned to using both 12 and 24V coiled relays…

Intawesting. So A1 has same 12v relay as A0? and same 12 and 24's on the A1r?

 

[Ronmar]

Intawesting. So A1 has same 12v relay as A0? and same 12 and 24's on the A1r?

They should be, they are standard automotive relays…