We have a cat th103 sn3pn593. After years of electrical issues due to a chopped, and spliced harness the decision was made to purchase a new one. I've installed it everything works, but it will not engage the transmission. I've checked everything on the machine having to do with the control circuit of the trans. I cannot find any issues. Can anyone help point me in another direction. After 2 days I'm not any closer to resolving the problem.
Can't really help much other than to offer you an electrical schematic if you don't already have one.
Thank you for your response, nige. I do have the schematic. Mabey a stupid question, but can a latching relay be bad even if the contacts move as they should? I honestly don't know what else it could be. It's like the trans is locked out from the parking brake, but everything seems ok.
Just a thought did the harness update? just wondering if there was a special instruction that went with the up date
Good point. What's the old/new harness Part Number.?
I'll have to look in morning. I had thought of that, but really couldn't get a definitive answer from anyone. In desperation I was going to look at all the 37 pin connections to see if the wires match up. Will get the number tomorrow. Thanks
Th103 S/N 3pn593
OK, so what I can see is that the 141-8038 dash panel wiring harness shown on the electrical schematic is shown as discontinued - no idea why. The 183-3050 in your photo is a replacement for 166-9095 but I cannot tie any of those two Part Numbers back to 141-8038. There are no Service Magazines that mention any of the three numbers, so that leaves me somewhat at a loss. I can only agree with your suggestion to check the pinouts everywhere on the new harness against what is shown on the schematic. It wouldn't be the first one I've seen out of the Parts system that was manufactured incorrectly.
After a phone call, and a hour of looking at wires numbers with a magnifying glass. I discovered the new harness is last serial number break. It's close,but there are a few things different from the old one. I'm not sure what is different from the new harness to the transmission harness, but at least it's progress. It's just weird everything else works, but the transmission.
just wondering does this machine have a neutral button I saw some thing about a change to control stick it said some thing about removing and discarding a small harness and I'll be damned if I can find it now
No, it's just a basic open cab machine. There is a transmission neutralizer in the harness, but nothing to connect it to.
Their being nothing connected to it might be a problem you would think a jumper plug
Mabey with the new harness . I'll have to look at that. The old one had the same plug,but had nothing connected to it either.
that's funny they usually don't leave a plug open even if they just put a dummy in it
I’ll have to check up on that but I could’ve sworn that Part Number harness was correct for the machine Serial Number. EDIT: 183-3050 is shown as the correct dash panel harness Part Number for any machine with an Open ROPS and S/N between 3PN530-2026.
Yes the relay can latch and nothing will pass through it if the contacts are too black or too worn out. Have seen a large one fail in one week, and wasted a bit of time only to find out the new Cole Hersee solenoid was junk. Easy to check. Simon C
Some telehandlers have a transmission disconnect tied into the brake system. If you step on the brake, the transmission goes into neutral.
As the Chinaman would say - Sum Ting Wong. See my earlier post. From another TH103 electrical schematics the dash panel harness for Open ROPS machines is listed as 166-9095 (updates to 183-3050) for machines from S/N 3PN996-Up, actually from 3PN996-2026, then a different schematic for machines from 3PN2500-Up calls out a 173-2334 harness. So I guess what I'm saying is to confirm what you already know that the 183-3050 harness is for machines with S/N above 3PN996. Attached the schematic in question. Maybe you can use it to compare the pinouts of the two harnesses, especially in respect to the transmission control. Also take a look at the jumpers on the "FUNC LOCK CONN PLUG" right next to it.
Thank you for all the replies to my problem. I'll check on everything when I get back to work tomorrow. One other thought I had. If the new dash panel harness is for a higher serial number machine, would it be compatible with an older frame harness? I'll have to see if the pins going to the trans harness are in the correct places .
I've made some progress. I jumped the transmission neutral switch, and got the transmission to engage. My current issue is it will go in gear with the park brake on or off. Will order a proper switch and see if it solves the problem. Thanks again for all your help.
Looked at your schematic for a while. Guessing you ordered Part#111-7898 Neutral Switch. There is a lot of ground connections on that schematic, lots up in dash and all over. Should be having a good look at most of them and clean up any that aren't pretty. Your Transmission Neutralizing Relay found in section L-17 of schematic could be metered between Pin#1 and Pin #10 . Could find something wrong there. Easy check. Simon C
I cleaned all the grounds. I'm still trying to wrap my head around the concept of a jumper wire bypassing the park brake. Hopefully the switch solves that.