Joey Mack

ok... Not good..... Is the oil pump new? if the pressure regulator piston is gauged really bad it will reduce oil pressure. A broken spring is rare but possible.. I have had PAI oil pumps deliver around 10-PSI less pressure but still in range.. Remind us, please... did you roll rods and mains? jojo

I wish I had one of those, back when I was doing road service work.. Heck, I never even thought to look into buying one... $88.00 What a deal!! jojo

What I mean is that, the truck pressure sensor goes through the EECM.. but a hand held gauge is actual.. if the hand held gauge is reading a different pressure, hopefully higher, then there may be an issue with the trucks sensor.

I don't remember if you had put a gauge on the oil gallery to compare it to the EECU reading..? Jojo

were you able to fix the issue? and have brake lights working again? jojo

there is no gasket, just shims and rtv... the smaller seal housing directly behind the yoke may have a gasket or o-ring, but if it is not leaking, then there is no need to remove the yoke... dont go heavy with rtv, you dont want to change the bearing preload.. jojo

Looks like the input housing is loose. The bolts are 16mm or 5/8 12 point.. you can pull it out as a unit, clean the steel shims, Be careful, they will cut you... Then lightly apply Mack Gray RTV to the shims and re- install it.. I believe the bolt torque is 175 lbft.. when you handle the shims, pay attention to the oil gallery holes in the shims.. make sure you don't cover the holes, by accidently rotating a shim in correctly.

Try this company on the web. HDP, 888-919-pros, Tune up kit P/N: 4559-18678... Hopefully they have what you need in stock..

My guess is the Brake series is Jacobs 680? What issues are you having?

I have 2 here now, one that is burned up... yes.. You are right... i have 2 harness's to repair... I bet I make 1 out of 2... A good solder iron and heatshrink can make a $1200.00 harness new 'enough' to use again, and beat the Volvo B.S.. jojo

I have posted my opinion a few times... Why???? because a harness is not in stock, and it is over a thousand dollars... If you take the time to ohm it or just plain remove it and string it up in your shop or a room in your house if you have too.. and check every wire related to the fault codes or just every wire.. yes it is tedious and takes hours... but it doesnt cost thounsands of dollars... buy a cheap ass dvom from harbor frieght, and you can buy good wire and terminals and heat shrink at NAPA, and make pro repairs.. and as far as 'pin tension' in the plugs... you can improve the connections with a cheap ass, pick set.. from harbor freight.. .. jojo

Are you able to test your harness and repair the faults that you find within the harness? I have taken wire harness's and ohm'd wire's end to end and a physical inspection of integrity, on the plug ends and the tightness and tension of the terminal's.. and made repair's. Since it is an '04 , the wires are all white and have the path printed on them, so you can pick a plug end, and write down the wire code, and follow it to its end and use the code flow chart to find an issue within the circuit. Lot's of word's here but if you think about it... it's not really complicated... jojo

The brake light pressure switch on an RD, is on the fire wall under the hood.. in the center.. Beware, it is hot all the time regardless of ignition position.. Jojo

thank you for posting the solution.... It will help someone else with the same issue... jojo

That is great news... Thanks for the respect, But it is Truly a team effort here at BMT.. Many guys here that are ready to help... Jojo

wouldnt a 2 1/4'' do the trick.??

Thank You O.D. From: Terri...

the red button is not part of this issue Mech.. It is a seperate switch, that only controls the rear air bags.. its actually a simple system, especialy on a 90's truck...

well that is correct... they will not rise until tractor protection valve opens up to supply air to the other systems..... only the brakes get the air above 25 PSI... It is a safety feature in big trucks...

I have also seen the filter screen inside the air input port on the leveling valve, blocked up with red dirt... I guess southern red dirt can travel throught the smallest places...

there is an exh. port on the leveling valve

mech, with respect to him. He did say he was new at this.. its all good

10 seconds

the air switch takes air from the tank through a regulator in a pro set-up. then sends it to the leveling valve to the 'pilot' port.. the valve dumps the air for you, so you can hook or unhook. then flip the switch and suspension rises to a preset level..