MACKS Posted April 24, 2021 Share Posted April 24, 2021 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.. Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted April 24, 2021 Share Posted April 24, 2021 is there a fuse for it? is there power to the dash switch ? Quote Link to comment Share on other sites More sharing options...
MACKS Posted April 24, 2021 Author Share Posted April 24, 2021 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? Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted April 24, 2021 Share Posted April 24, 2021 (edited) 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 April 24, 2021 by Joey Mack More content needed 1 Quote Link to comment Share on other sites More sharing options...
MACKS Posted April 24, 2021 Author Share Posted April 24, 2021 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.. Quote Link to comment Share on other sites More sharing options...
Swishy Posted April 24, 2021 Share Posted April 24, 2021 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 1 Quote Link to comment Share on other sites More sharing options...
Hayseed Posted April 24, 2021 Share Posted April 24, 2021 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.. Quote "Be who you are and say what you feel...Because those that matter...don't mind...And those that mind....don't matter." - Link to comment Share on other sites More sharing options...
MACKS Posted April 25, 2021 Author Share Posted April 25, 2021 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.. 1 Quote Link to comment Share on other sites More sharing options...
fjh Posted April 25, 2021 Share Posted April 25, 2021 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 2 Quote Link to comment Share on other sites More sharing options...
MACKS Posted April 25, 2021 Author Share Posted April 25, 2021 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. Quote Link to comment Share on other sites More sharing options...
tjc transport Posted April 25, 2021 Share Posted April 25, 2021 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 1 Quote when you are up to your armpits in alligators, it is hard to remember you only came in to drain the swamp.. Link to comment Share on other sites More sharing options...
Popular Post Dirtymilkman Posted April 26, 2021 Popular Post Share Posted April 26, 2021 On Jakes I always check them by running battery voltage right to the head where the wire comes out. Then you can decide which way u need to go. 2 1 Quote Link to comment Share on other sites More sharing options...
MACKS Posted May 12, 2021 Author Share Posted May 12, 2021 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? Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted May 12, 2021 Share Posted May 12, 2021 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? Quote Link to comment Share on other sites More sharing options...
MACKS Posted May 12, 2021 Author Share Posted May 12, 2021 Just two screws to the switch,I’ll get some pictures tomorrow, thanks. Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted May 12, 2021 Share Posted May 12, 2021 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.. Quote Link to comment Share on other sites More sharing options...
Swishy Posted May 13, 2021 Share Posted May 13, 2021 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 Quote Link to comment Share on other sites More sharing options...
fjh Posted May 13, 2021 Share Posted May 13, 2021 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! Quote Link to comment Share on other sites More sharing options...
Swishy Posted May 13, 2021 Share Posted May 13, 2021 FJH thanx for the info it was runnin fine the way it was we also use the EB to kill revs when we R skip shift n cya Quote Link to comment Share on other sites More sharing options...
MACKS Posted October 2, 2021 Author Share Posted October 2, 2021 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? Quote Link to comment Share on other sites More sharing options...
mrgumby Posted October 2, 2021 Share Posted October 2, 2021 (edited) 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 October 2, 2021 by mrgumby Quote Link to comment Share on other sites More sharing options...
MACKS Posted October 2, 2021 Author Share Posted October 2, 2021 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 Quote Link to comment Share on other sites More sharing options...
MACKS Posted October 2, 2021 Author Share Posted October 2, 2021 My switch is doing the exact opposite,think I’ll get a new one and go from there. Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted October 2, 2021 Share Posted October 2, 2021 (edited) 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 October 2, 2021 by Joey Mack 2 Quote Link to comment Share on other sites More sharing options...
MACKS Posted October 3, 2021 Author Share Posted October 3, 2021 I took a close look and only two posts but I also saw a hairline crack the length of switch.. 1 Quote Link to comment Share on other sites More sharing options...
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