MCI-9 Rear Junction Box

[Kwajdiver]

I need someone to look on the inside of the MCI-9 Rear Junction Box cover and tell me what the label says across the bottom.  Should find several breakers, with numbers, and Item on the bottom.

Thanks in advance,

Bill
Still in Gulfport, Ms

[gumpy]

I have a diagram of the circuit breaker locations in the rear J box. Is that what you need?

Two rows of breakers.

Top row left to right: Tachograph Clock - 3 amp, Lavatory Buzzer - 6 amp, lavatory Lights, Motor Comp Lights - 6 amp, Reverser Solenoid - 15 amp, Alternator Field Circuit - 15 amp, Tail Lights (CCT. No. 15) - 6 amp, License Plage Lights - 3 amp, Spare - 6 amp.

Bottom row left to right: Tacograph, "Run Switch" - 6 amp, Engine Stop CCT - 6 amp, Air Cond. Control - 15 amp, Lavatory Blower - 3 amp, Back-Up Lite - 6 amp, Temp & Level - 3 amp, Spare - 6 amp, Spare - 6 amp

[Kwajdiver]

Grumpy,

Thanks for the input.  So the bottom left Spare, does it have any wires on it?  Perhaps two wires....
What year is your bus?

Stud 39 in the top, one wire, two wires, nothing?  My has one wire, it is black with a 5 on it.

Thanks for the help.

Bill

[Kwajdiver]

65, not 5 is the wire number

[gumpy]

So the bottom left Spare, does it have any wires on it?  Perhaps two wires....
What year is your bus?

Stud 39 in the top, one wire, two wires, nothing?  My has one wire, it is black with a 5 on it.

This info was from the manual decal page. 1-1-1989. 
I haven't looked in my bus box yet. I'll go out and look at it tomorow. Hopefully it'll be warmer.

Are you saying stud 39 goes to the spare circuit breaker with wire 65?

In the 1989 manual, Stud 39 says circuit 15B, Red-Blue - Marker Lights on separate toggle switch. There's no circuit 65 listed in
the manual.

In an older manual dated Jan. 1980, Stud 39 is circuit #65, White-Brown, 16 ga, Reverse Solenoid Relay.
There's also a Relay with circuit #65, Maroon, 14 ga, Reverse Solenoid.
The circuit breaker page is the same as in the 1989 manual, but is dated Jan 1979, effective unit no. 34001.

[Kwajdiver]

Are you saying stud 39 goes to the spare circuit breaker with wire 65?  No,,,,    Just need to know if you have more than one wire on stud 39.

Thanks,

Bill

[gumpy]

Are you saying stud 39 goes to the spare circuit breaker with wire 65?  No,,,,    Just need to know if you have more than one wire on stud 39.

No, that's not what I'm saying. The information I provided came from the two manuals. It just says what circuit 65 is, and what stud 39 is. It also says which position the relays were installed in originally. It's entirely likely that someone has moved a wire on your bus in the past from the reverse solenoid circuit breaker to the spare. Possibly the reverse solenoid breaker broke or stopped working.

I went out and looked at my panel. I have one wire on stud 39, which makes sense as my bus is a 1982, and came with an automatic transmission, so reverse solenoid would not have been installed or connected.

I also do not have a right hand spare relay on the bottom row, only the left hand one, and it's broken and not used. I'm missing several other relays that were not used, or were removed when I pulled the interior.

In looking at this again, I realize that I need to put these relays on my to-do list. They are in sad shape, and some have broken and are actually
being bypassed. Not a good thing.

[Kwajdiver]

Thanks for the input.

New question,   where is the Engine Terminal Block?   Where is the FAST IDLE VALUE?

Guess that is two question.  Trying to figure out, why I've lost my Fast idle.  Both the toggle switch and the air switch are working.  Traced it back to stud 22 in the Rear Engine Compartment.

Thanks for the help.

Bill

[gumpy]

According to the manual, fast idle comes from front busbar 6 amp circuit breaker, to stud 26, FJB (front junction box). Wire 39P goes to emergency brake air switch. Wire 40P leaves e-brake air switch and goes to FJB stud 47, and on to fast idle switch. Wire 40 leves fast idle switch to FJB stud 46, to RJB stud 22, to Engine Cradle Harness Plug A, and to Fast Idle Valve.

By air switch, I assume you mean "Emergency Brake Air Switch".

My experince says the most likely culprit is the fast idle valve, or the fast idle air cylinder itself.

Do you have the "Motor Control Wiring" schematic?

[Kwajdiver]

Yes,  I have the schematic for that.  Yes, it does as you stated.  However, off the RJB stud 22 it also goes to the Neutral Relay, upper left hand corner of the RJB.

Where is the Engine Cradle Harness Plug A and where is the Fast Idle Air Cylinder?

Thanks,

Bill

[gumpy]

Yes,  I have the schematic for that.  Yes, it does as you stated.  However, off the RJB stud 22 it also goes to the Neutral Relay, upper left hand corner of the RJB.

Where is the Engine Cradle Harness Plug A and where is the Fast Idle Air Cylinder?

Ok, I went out and got my other manual from the bus. The Motor Control Wiring diagram is dated Jan 1989. It shows wire 40 leaving FJB stud 46, and going to screw terminal 8 on Neutral Relay. It exits neutral relay on screw terminal 6 and goes to RJB stud 22 and continues on to Fast Idle Solenoid Valve as before. This was evidently an addition to keep the fast idle from being engaged unless the transmission was in neutral. Not sure when it was instituted. Obviously after May 1979, which did not show it. My 82 has it wired with the neutral relay.

The engine cradle harness plugs are in the lower corner of the rear junction box. Bendix military style connectors. Look around the corner at the engine side of the box.

Test the neutrel relay. Make sure it's activating when the tranny is in neutral.

craig

[Kwajdiver]

I found that same thing on the Neutral Relay.  Seem I have a problem  Pin 1 only has 7 volts on it from stud 15.

Relay pins 7, 8, 2 all have 24 volts.  6 has no voltage,,, hummmm that can't be correct.  Perhaps the relay is not pulling down.   

Bill

[gumpy]

I found that same thing on the Neutral Relay.  Seem I have a problem  Pin 1 only has 7 volts on it from stud 15.

Relay pins 7, 8, 2 all have 24 volts.  6 has no voltage,,, hummmm that can't be correct.  Perhaps the relay is not pulling down.   

Bill

Check screw terminal 5 on the relay. If the relay is not engaging, you should have 24 volts out terminal 5.

There shouldn't be any voltage on stud 15 unless you are engaging the starter button. There may be some feedback to it, which might account for the 15 volts, though I don't immediately see a path for it to feed back on.

[Kwajdiver]

Good news,   I grounded Neutral Relay screw 2.  That corrected my fast idle. Then I connected the wire off screw 2 to ground.  My shift pad lights up,,,,    The DO NOT Shift light is on,,, I still can not engage the transmission. But, I've got to be getting close to the problem.

The wire from the relay screw 2 goes to the shift pad pin 11. Which is the Do Not shift light.   Must be something else here, that I'm missing.  Doesn't show it on my print.  Of course, my prints are way off.

Bill

[gumpy]

So your relay is not getting grounded.

My manual says that the BLK wire goes from terminal screw 2 on the Neutral Relay, through the Engine Cradle Harness Plugs, to the tranny neutral switch, to ground.

I don't have any diagrams for electronic shift pad as you describe. I assume this is for the ATEC you mentioned in the other thread?

Maybe your tranny neutral switch is not grounding the relay, or the ground wire is not connected. Not sure if it's a separate wire from the tranny switch, or if the switch grounds internally. It appears from my manual that the ground wire comes back from the tranny switch, though the Cradle Harness plugs, and grounds in the RJB.  Check the ground lug at the bottom of the RJB. Might be corroded.