I recently purchased a 2002 cat 246 skid steer (s# 5SZ04301) It had quite a few electrical problems. The previous owner had jerry rigged it pretty good. At the time of purchase the parking break and seat belt lights were flashing. So the machine would not travel and the bucket would not operate. I took it to cat to see if they could help me narrow down the issue. They replaced the ecu??, computer behind the cab. They said that fixed my issues and the machine was operating. I went to pick it up and the machine was acting the same as before and would not release the parking brake. So not sure whether cat was pulling my leg or not but i had a $1500.00 bill and a non functioning machine. I did some research on here and and followed some troubleshooting trees, testing resistence, and voltage. Everything told me to change the wiring harness, and considering the shape it was in i agreed. After replacing all the harnesses, the parking brake will disengage and the machine will travel but i do not have bucket controls.I have checked the work tool solenoid it is showing 10 ohms. The work tool detent coil looks pretty rough, and is showing OL. but i was told that should not cause the problems i am having.Does anyone have any ideas?? I would appreciate it. Everytime i call cat to ask some questions, they are less than helpful and seem unwilling to give me too much info. Again any ideas would be appreciated
Do you have the electrical schematic..? It has the resistances of the various solenoids plus switch specifications, etc. lf you would like a copy send me a PM (conversation) with your email address. I'll send it to you.
PM Sent, hopefully i did it right !
You did. Email on the way.
I just checked my email, wasn't sure if you sent the schematic or not?
I replied to you early this afternoon (2:00PM EDT give or take) to the same email address contaned in your PM. Please double check that your email server has not diverted it to your junk folder. Also double check the email address you sent to me via PM is correct.
I still not seen your email come thru. I did pm you a different email address to try if you wouldn't mind... forgetting my email issues! I did work on the cat a few hours today. I'm starting to think I might have a bad ecm?(behind the cab) I figured out I was losing voltage at the harness for the work tool solenoid.(only 4.5 v) so I traced it all the back to the Ecm harness.I believe I have found the power-in wire, can't remember the number, but it is showing 12 VoltZ and everything else from the harness is 7.5 to 4.5 VoltZ. Is there a way to test if the ecm has failed? I also ran a jumper wire straight to the work tool solenoid from the battery. With the solenoid getting 12 VoltZ everything worked fine. So Im guessing my problem seems to attached to the low voltage coming from the ecm.
Before you condemn the ECM. isolate the detent solenoid from the circuit and retest. The detent and pilot solenoid are in parallel and a fault in one will pull the voltage down Mark
I attached a picture of my work detent coil, i originally thought that might be the issue, but i was told by a service tech at cat, that the coil shouldn't be causing the problems i'm having. Would that coil cause low voltage to whole system? I'm getting low voltage in other areas than just the right joystick. Thanks for the help
the coil could cause your problems but what do you mean lose of voltage in other areas do you mean the transmission solenoid ,start relay, park brake solenoid, and how are you checking these voltages? Have you bypassed the interlocks to test these circuits? Have you confirmed that you have good grounds and common returns? ,is the ECM grounded? Mark
Your Cat service tech is talking out of his backside. The interlock system will not work if that coil is faulty. When you power up, what combination of park brake/armrest lights are you getting? I walked someone else on here through the troubleshooting several years ago. I'll try and find the thread.
Here we go. Check out post #6 onwards and see if it helps. HeavyEquipmentForums
Other than the initial start up lights. I am not getting any lights on the instrument panel. Parking light comes on after start up but turns off after you hit the switch. I'll look into those posts tomorrow and yet you know where it takes me.
Mark250 I tested the voltage from the wiring harness connection at the right joystick with the seat and park brake unlocked. It showed 4.5 VoltZ. I believe it was wire or 988. I followed it back from the right joystick to the ecm and at all the connections that wire showed 4.5 VoltZ and coming out of the ecm was the same. I test several other wires coming out of the ecm and the voltage appeared low as well. I did not bypass the interlocks. I have checked the grounds behind the cab, next to the hyd pump and in the engine bay, are there any more? Cause the three I know about all seem to be good. Ecm is looks to be grounded good as well. I'm definitely a novice when it comes to electrical work. I could be doing it all wrong, but once I get 12 VoltZ to the work tool solenoid everything works fine.(jumping it straight from the battery) Would you recommend replace the work tool decent cool and seeing where that gets me? Thanks in advance
yes replace the detent coil but for diagnostic purposes un plug the detent coil and substitute with a 10 ohm resistor and try Mark
I substituted the detention coil with a 10 ohm coil and nothing changed. I changed a couple of the solenoid son the control value and still nothing. I'm still showing 12 VoltZ coming into ththe computer from the power wire but only getting 7.5 to 4.5 VoltZ coming out when I back probe all the other wires. I also unplugged all solenoids on right joystick and control value and the harness was still showing only 4.5 VoltZ. Any ideas?
from your post #13 you stated, that after key on all lights came on briefly then are initialization indicators went out except the park brake indicator.you then operated the park brake switch and the park brake indicator went out this indicates to me that the lock out circuit (seat switch, door switch and armrest) is working OK have you checked the operation of the hydraulic lockout switch if fitted. if not is the jumper wire that replaces the switch installed. to confirm check that you have continuity between wire #E917 from the ECM and ground or just ground that wire at the ECM Mark
Unplug the coils that are fed by the circuits you are back probing. You are measuring voltage drop from the work on the circuit. Unplug it at the coil and backprobe it at the ECM and at the coil connector and see what your voltage is
if you unplug the coils the ECM will see this as a circuit fault and the interlock system will isolate the circuits and as stated earlier the OP has already done this. also the indicator lights will flash indicating a faulty circuit which he also states that no lights are on the lock out switch circuit is not monitored by the ECM to indicate faults in this area Mark
I ended up taking it to cat, after running into dead ends, they tested the ecm and said that it was bad. Everything is working after replacing the ecm. Thank you all for all the help