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Engine Brake?


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Can anybody tell me how to trouble shoot the engine brake on a 96 cl E-7,switch on the dash is working,I jumped the wires going to the clutch pedal switch,nothing,should one of those wires be hot and should one of the wires on the pump switch be hot,I have no voltage going to the pump switch..

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1 hour ago, Joey Mack said:

is there a fuse for it? is there power to the dash switch ? 

Fuse is good,voltage going to switch on dash and leaving also,no voltage going to switch on pump,the springy thing on clutch switch is broke of so that switch is activated always,where does the voltage go first pump switch or clutch or both at the same time?

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i beleive it goes to the clutch switch first then to the inj. pump. Is yours "full mechanical"? where is power missing? also. is it jacobs 680 brakes or dynatard?

Edited by Joey Mack
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4 hours ago, Joey Mack said:

i beleive it goes to the clutch switch first then to the inj. pump. Is yours "full mechanical"? where is power missing? also. is it jacobs 680 brakes or dynatard?

Ok thanks,I have to start over and see if I have voltage to the clutch switch first,will report back in a few days..

 

 

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Rule #1 When driving only use engine brakes when engine is @ operatin temp...

by pass the clutch switch by connectin the 2 wires together

when u get the EB workin then reconnect to clutch switch n sort out problem ... may B adjustment on the micro switch

cya

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6 hours ago, MACKS said:

Fuse is good,voltage going to switch on dash and leaving also,no voltage going to switch on pump,the springy thing on clutch switch is broke of so that switch is activated always,where does the voltage go first pump switch or clutch or both at the same time?

I think that the highlighted bit above MAY be your Problem..

 

For your Jakes to work that switch's contacts need to be Closed. Which is what the Clutch pedal holding the Springy thing Does. With that Broken Off I reckon the Contacts are now Open..

 

I'd do what Swishy Suggests & make up a Little Jumper wire & bypass the Clutch Switch. Or just Hold (Or Tape) the remains of the little lever Down. & see if they Work..

"Be who you are and say what you feel...
Because those that matter...
don't mind...
And those that mind....
don't matter." -

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10 hours ago, Hayseed said:

I think that the highlighted bit above MAY be your Problem..

 

For your Jakes to work that switch's contacts need to be Closed. Which is what the Clutch pedal holding the Springy thing Does. With that Broken Off I reckon the Contacts are now Open..

 

I'd do what Swishy Suggests & make up a Little Jumper wire & bypass the Clutch Switch. Or just Hold (Or Tape) the remains of the little lever Down. & see if they Work..

Thanks,with the spring broken the switch is in the on position,also I did jump the two wires and nothing,l should of checked for voltage at that switch also but I didn’t,now hopeing the problem is in between the dash switch and the clutch switch because forget about tracing the rest of the wires,they go thru the harness..

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19 hours ago, Joey Mack said:

i beleive it goes to the clutch switch first then to the inj. pump. Is yours "full mechanical"? where is power missing? also. is it jacobs 680 brakes or dynatard?

this question Joe asking  is important! older trucks used a Relay on the dynatard system!

Just sayin

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37 minutes ago, fjh said:

this question Joe asking  is important! older trucks used a Relay on the dynatard system!

Just sayin

It’s a Dynatard on a 1996 e-7 mechanical engine.

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om my 89 300 with a dynatard, something in the injector pump was bad. 

it would bend the plunger rod on first use. 

pull it out, straighten the rod and put it back in. first use it would bend the rod again.

mack could not figure out what was wrong with it, and it was already out of warranty when it broke. 

so i pulled the wire off the pump, and ran it into the cab to a two speed rear switch on the stick. the other side of the two speed switch was grounded. until the truck was 

worked like that for 15 years until we traded it in on a new RD tractor. 

i just don't remember if the 89 had an E6 or E7 in it though

 

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when you are up to your armpits in alligators,

it is hard to remember you only came in to drain the swamp..

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  • 3 weeks later...

I found a little time to mess with it,now I’m more confused than ever,Dash switch has voltage and works fine,clutch switch has voltage so I jumped the wires to by pass the switch,now down at the pump switch I get voltage on the one wire when the throttle is opened and when closed it shuts the voltage off,to further confuse me the two wires going to the heads are grounded,how do you get voltage thru grounded wires?

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the wires arent plugged onto the engine brake celenoid plug on the valve cover spacer.???   also, does the switch on the pump have 3 screws but only 2 wires?    is there a pic of the pump linkage and the wires that go to the valve cover?

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ok.. cool. i wonder if you have a diode in that switch,,, also, are the screws stamped with any abbreviations at the poles? catch you later..

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Th@ reminds me wot FJH sed

RE: this question Joe asking  is important! older trucks used a Relay on the dynatard system!

our mack R maxn out to get some resonable MPH @ 2100RPM

the govonor seems to B bouncin in n out so we switch off the EB so it dont burn the relay contacts

when flat run n

cya

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10 hours ago, Swishy said:

Th@ reminds me wot FJH sed

RE: this question Joe asking  is important! older trucks used a Relay on the dynatard system!

our mack R maxn out to get some resonable MPH @ 2100RPM

the govonor seems to B bouncin in n out so we switch off the EB so it dont burn the relay contacts

when flat run n

cya

Swish that condition can usually be tuned out by backing the screw out a turn or so on the back of the pump where the wire goes!

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  • 4 months later...

Ok, back to this,I have the clutch switch jumped,the switch on the pump has two wires one is a ground,if I open the throttle the button comes out and I have 12 volt on the one wire but no voltage going to the heads,is this correct or is it working backwards?Pump switch shot maybe?

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The switch on tr pump needs to be pushed in to complete the contact when you take you foot off the throttle it rests on the switch to push it in to complete the contact.   Now you said one wire on the pump switch is aground?  You don’t have 12 volts going through the switch  to a ground.    Not correct.   Usually on the wire going to the head they  put a bleed off resistor to ground along with the 12 +volt wire going to the head    You should have 12+ voltage going through the switch with the pump linkage resting on it to close the switch to complete the circuit   When you step on the throttle the switch open breaking the circuit

Edited by mrgumby
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10 minutes ago, mrgumby said:

The switch on tr pump needs to be pushed in to complete the contact when you take you foot off the throttle it rests on the switch to push it in to complete the contact.   Now you said one wire on the pump switch is aground?  You don’t have 12 volts going through the switch  to a ground.    Not correct.   Usuall on the going to the head they wire the put a bleed off resistor to ground along with the 12 +volt wire going to the head    You should have 12+ voltage going through the switch with the pump linkage resting on it to close the switch to complete the circuit   When you step on the throttle the switch open breaking the circuit

 

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look at the back of the switch ... some of these switches have 3 post's on them, 'common' ... 'normally open'....'normally closed' move the wire eyelet to NC, ... jojo

Edited by Joey Mack
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