Mark Buller
Member
- 15
- 12
- 8
- Location
- Darlowo, Poland
I am in need of some help with the installation of this winterization kit for the Cat 7155 transmission-- control block strip heater kit on my M920 & M916 Trucks. The kit came with 4 pages of diagrams--but only of the included items in the kit --NOT how to install it in the vehicle. I see that the strip heaters are clamped to the transmission control block and that there is a light installed in the cab showing the heating system is ON. However, there is no discription of HOW the system works NOR any instructions exactly how to install this kit . There are various components in the kit: 3X oil pressure sensor/switches, 1X temp. sensor/switch. 1X magnetic relay switch, wiring harness, the strip heater bars with insulation and covers, signal light for the cab, brackets & misc. hardware etc. I assume the magnetic relay is to provide main 12VDC power to the heaters....and I assume one oil pressure sensor/switch provides a 12VDC signal voltage to the magnetic relay to "close" (thereby supplying current to the strip heaters) with the other terminal of the magnetic relay going to a temp sensor mounted on the top of the transmission control block...this I assume is the GROUND for the magnetic relay ....i.e. when the control block is COLD, the temp sensor/switch is "closed " (providing a Ground) and when the control block is warm , this temp sensor switch...breaks the "ground" for the magnetic relay ....thereby opening the magnetic relay contacts---and cutting the power supply to the heaters i.e shutting the heaters off. But where do I draw the main 12VDC power supply from going to the magnetic relay?? - the main + terminal of the 12V Battery? I also assume, via one of the oil pressure sensor/switches provided, that signal voltage is only supplied to the magnetic relay (i,e, closing the contacts) with the engine running , so that the current supplied to the heaters, is provided by the Alternator rather than the vehicle batteries?? But there are 3ea, oil pressure sensor/switches/sending units included in this kit. What is the function of these other two? One, oil pressure sensor/switch/sending unit (titled: "Sending Unit") has P/N 1977-5965573, another oil pressure sensor/switch (titled: "Switch,low oil {pressure}) has P/N 1977-MB308B20000, and the third oil pressure sensor switch (titled: "Switch,oil pressure") has P/N 1977-MA308-20009. I wrote the supplier of this kit to the U.S. Govt, "Wheeler Fleet" ,384 Drum Ave. Somerset PA. and got NO response!! I would greatly appreciate any help anyone could provide. Perhaps someone has a truck with this kit installed and can tell me or make a few fotos of how this is all hooked up and if they have experienced any problems with shifting....ONLY....when the Transmission is COLD . Thanks in advance! P.S. I am thinking about installing this kit BECAUSE I have trouble shifting the transmission into nearly ANY gear on both my M920 and the M916 Trucks BUT ONLY WHEN THE OUTSIDE TEMPRETATURE DROPS BELOW SAY about 50-55 degrees F ,--i.e, NO PROBLEMS SHIFTING IN SUMMER even upon initial morning start up... BUT COOL Fall days or early Springtime ---BOTH transmissions do not want to shift into gear! I read all the other Cat 7155 Blog comments posted on Steel Sol. about oiling and pressure reg. etc. AND I AGRREE, I will also try these suggestions. But that I ONLY have these shifting problems when the transmission is COLD leads me to think that perhaps this heater kit could be the long term solution????
