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I'll start by referencing an old thread "CTIS 5 flashing lights,No air leaks, no mechanical faults" I posted on that thread a couple months ago but unfortunately didn't get any responses. Probably because everyone that originally were responding to that thread 8 years ago are no longer active. I wish these older threads that haven't seen any action in say a year would show up like a new thread so everyone would get an email notification and get the opportunity for fresh eyes to look at the problems.
I will try to keep it short by saying I've been working on this problem for some time now.
Working on a 2003 M1078A1 with the M1079 van body on it.
After years of it working perfectly and 6 months on the road full time traveling 12-13,000 miles. One morning I got 5 flashing lights.
I know, major air leak is typically the problem. While on the road I did some simple trouble shooting by removing the output airline from port C on the Pneumatic Control Unit (PCU) and applying shop air to the lines to locate the leak. After looking and listening and spraying soapy water everywhere no leak found and I decided it would have to wait till I get home to my shop to do further trouble shooting.
Knowing the age of the vehicle and after traveling a total of over 14,000 miles, I decided to order all new CTIS seals and hub seals to rebuild all the hubs. Also I have new Aluminum wheels with freshly rebuilt CTIS wheel valves ready to go. The other night I finished rebuilding the hubs and installing the new wheels. Time to crank it up and test it!!!! I was so happy the CTIS came alive and worked perfectly. The next day I realized I had the low pressure transducer switched on. Again cranked it up switched to the high pressure transducer and the CTIS worked perfectly airing the tires up to 85psi. Next morning I go to take it for a long test drive to check hub temperatures and the CTIS is back to its old problems, 5 lights flashing. After trouble shooting everything possible with out the ability to connect with a computer to get trouble codes. I'm currently at a dead end. With a cap on the PCU output port C, on start up the CTIS highway mode light blinks a few times as its doing its sampling then the highway light stays on solid as normal. While trying to find an air leak I was isolating the leak potential by removing the rear air supply line to the Quick Release Valve (CRV) and capping it off. Still had the 5 flashing lights so I removed the front air supply line from the front CRV and capped it off. Still no luck 5 flashing lights, so the air leak must be at the bulkhead fitting or where the line splits and goes front to rear. I applied 120psi shop air to the output line from the PCU, sprayed soapy water test and NO leaks anywhere. Reconnected the air line to port C on the PCU with the front and rear lines capped off just before they go into the QRValves still 5 flashing lights, put the cap back on port C and works normally add 20-30 of air line with no leaks and 5 flashing lights. What gives??? Im about to pull the PCU, pull it apart clean, lube, reassemble and see if it changes anything.
I will try to keep it short by saying I've been working on this problem for some time now.
Working on a 2003 M1078A1 with the M1079 van body on it.
After years of it working perfectly and 6 months on the road full time traveling 12-13,000 miles. One morning I got 5 flashing lights.
I know, major air leak is typically the problem. While on the road I did some simple trouble shooting by removing the output airline from port C on the Pneumatic Control Unit (PCU) and applying shop air to the lines to locate the leak. After looking and listening and spraying soapy water everywhere no leak found and I decided it would have to wait till I get home to my shop to do further trouble shooting.
Knowing the age of the vehicle and after traveling a total of over 14,000 miles, I decided to order all new CTIS seals and hub seals to rebuild all the hubs. Also I have new Aluminum wheels with freshly rebuilt CTIS wheel valves ready to go. The other night I finished rebuilding the hubs and installing the new wheels. Time to crank it up and test it!!!! I was so happy the CTIS came alive and worked perfectly. The next day I realized I had the low pressure transducer switched on. Again cranked it up switched to the high pressure transducer and the CTIS worked perfectly airing the tires up to 85psi. Next morning I go to take it for a long test drive to check hub temperatures and the CTIS is back to its old problems, 5 lights flashing. After trouble shooting everything possible with out the ability to connect with a computer to get trouble codes. I'm currently at a dead end. With a cap on the PCU output port C, on start up the CTIS highway mode light blinks a few times as its doing its sampling then the highway light stays on solid as normal. While trying to find an air leak I was isolating the leak potential by removing the rear air supply line to the Quick Release Valve (CRV) and capping it off. Still had the 5 flashing lights so I removed the front air supply line from the front CRV and capped it off. Still no luck 5 flashing lights, so the air leak must be at the bulkhead fitting or where the line splits and goes front to rear. I applied 120psi shop air to the output line from the PCU, sprayed soapy water test and NO leaks anywhere. Reconnected the air line to port C on the PCU with the front and rear lines capped off just before they go into the QRValves still 5 flashing lights, put the cap back on port C and works normally add 20-30 of air line with no leaks and 5 flashing lights. What gives??? Im about to pull the PCU, pull it apart clean, lube, reassemble and see if it changes anything.
