We recently purchased a Cat D5M dozer. Serial number 3CR01241. The previous owner had just replaced the engine and then started having brake issues where they would lock up. I do have access to the wire schematic and have been troubleshooting with that. I did try moving it yesterday and it seemed to be working fine for about 50 yards then started locking up again. Restarting it seemed to free up the machine for about 15 feet then it would lock up again. There are 15 codes on the machine mostly related to the braking and transmission system(mainly solenoids). I can post them if needed. Any help would be greatly appreciated.
Out of those 15 Codes which ones are Active.? In other words the SERV CODE icon is lit up when you scroll to that Code. Take a look at the Click Box thread. Pay special attention to Posts 50-52 on Page 3 where it shows you how to McGyver something to delete Logged (non-Active) Codes using no more than a couple of bits of wire. It might pay you to do that first. Then whatever Codes cannot be erased are obviously Active and that would be a good starting point for diagnostics.
I will check to see which codes are active in the morning. Will also checkout the post you recommended and get a click box made up. I will give an update when I find out more.
For a start you can manage with nothing more than 2 pieces of wire.
I did get most of the parts to build the clicker box. The rest should be here next week. I went through the codes and the only active one as of now is 030 0248.02 Data Signal Erratic. I did run the machine back and forth a number of times and initially it seemed to move just fine. Then started to hang up again. Restarted the machine and it started moving again. No new codes after doing that. I did some testing on the parking brake solenoids. The voltage going to the solenoid when switching the parking brake off is 7.5 volts. Does that seem right?
Attached is the troubleshooting procedure for 030.248.02 Not according to what I can see. It appears as though the park brake solenoid is supplied with Batt+ via the parking brake switch, so IMO you should have more than 7.5 volts. I'll send you the electrical schematic.
Nige I followed the power train troubleshooting guide you sent and took some pressures. By the looks of the schematic there are two ports to test the PV? Below are the results. Top Priority Valve port by filter cover Brake On at 850 rpm : 425psi (spec 138psi) Brake Off at 850 rpm : 425psi (spec 424psi) Brake Off at 2340 rpm : 451psi (spec 138psi) Lower Priority Valve port Brake On at 850 rpm : 140psi (spec 138psi) Brake Off at 850 rpm : 410psi (spec 425psi) Brake Off at 2340 rpm : 500psi (spec 138psi)
You need to be on the lower port, the one marked PV on the diagram. There are 6 tests in total: - 1. Parking brake ON. Low idle. 2. Parking brake OFF. Low ilde. 3. Parking brake OFF. High Idle. 4. Left service brake applied (hand control). High Idle. 5. Right service brake applied (hand control). High idle. 6. Both brakes applied (foot pedal). High Idle. The specs for all the above are in the T&A document.
Can you send me that T/A document again. I had lost everything you sent.
No problem.
Here are the results of the lower PV pressure test. Park brake on low idle : 95psi Park brake off low idle : 400psi Park brake off high idle: 505psi Left service brake applied high idle : 500psi Right service brake applied high idle : 500psi Both brakes applied (foot pedal) : 500psi
With gauges on the LH & RH brake pressure test ports repeat steps 4, 5, & 6 and post the brake pressure measurements.
LH brake applied : 0 psi. Released 400 psi RH brake applied : 0 psi. Released 400 psi Both brakes applied via pedal : 0 psi
Service brakes are working fine in that case. It would appear that the problem could likely be internal within the Priority Valve. The next step would be to remove it, open it up and inspect paying careful attention to the condition of the springs and the spool.
Can you explain briefly what the PV does?
It prioritizes the oil supply from the transmission pump to the steering/brakes over the transmission so that the tractor can never run out of brakes. The same section of the transmission pump supplies oil to both the brake circuit and the transmission.
Does this not sound like a transmission problem rather than a brake problem..? "The last couple times I tried running the machine it would work good for about 3-5 minutes then slowly fade to the point it wouldn't move at all. Here is the interesting part. I was on a decline at different points when it quit and the machine actually continued to roll down with no power applied. If it were the brakes it wouldn't move."