E7-400 Jake brake won’t work

[Richie253]

I have a CHR 94 model with an E7-400 motor that I cannot get the jakes to work. When I check the relay that connects the engine brake control module to the dash switch and clutch switch all poles have power on them 

[fjh]

Does it get power to the heads when operated?

[Richie253]

I don’t think so Not sure?? I have taken it for a drive and they don’t even come on 

[fjh]

Ya need to check for power at the head it may not be an electrical issue 

[Joey Mack]

You can pull the wire off the post at the head, and put a test light on the wire and ground it to the engine. no need to drive it or even run the engine, just turn the switch on and the light should light, with the key on.  you can run the engine if you like, and rev it up and let off and watch the light, if it lights on each post then the issue is likely under the valve cover...  jojo

[Joey Mack]

you can also use a jumper wire from a power source like the alt. pos. wire, and touch the post on the head and listen for a click sound, just to add to the diag... jojo

[Richie253]

2 hours ago, Joey Mack said:

You can pull the wire off the post at the head, and put a test light on the wire and ground it to the engine. no need to drive it or even run the engine, just turn the switch on and the light should light, with the key on.  you can run the engine if you like, and rev it up and let off and watch the light, if it lights on each post then the issue is likely under the valve cover...  jojo

Do you have any pics of the wires etc there are only two wires coming out of the rocker covers

[Jamkar]

That’s the wires that you need to check, One brake on each head (low and high). 

[Richie253]

11 minutes ago, Jamkar said:

That’s the wires that you need to check, One brake on each head (low and high). 

So is one earth and one power or both power?

[mrsmackpaul]

Both power Im pretty sure, grounds thru the motor 

 

Paul

[Richie253]

Can I bypass the module and run power just through the dash switch, clutch and throttle position switches???

[Joey Mack]

if you have an Ambach pump, they have a controller with a diode, I think on the firewall....  Did you run a hot wire with an aligator clip to the posts on the heads just to see if they work? Robert Bosch pumps have micro switches.... and no diode... (Glenn,) correct me if im wrong...