Hi all, You guys were super helpful last time I needed help, so I'll try again. My machine is a cat 943 sn 19z00916 with a 3204. I've got what looks to be a switch of some sort that taps off the right side of my head unit. I thought it was an oil pressure switch but I keep getting what I think is conflicting information in my manual. There's a diagram in my manual that shows the locations of the engine oil pressure switch, engine coolant temperature, fuel pressure switch, backup alarm switch, and transmission oil temperature switch. I only mention this because none of the above are in the same location as this switch. Also, looking at the small diagrams in my specifications section, it shows drawings/pictures of the trans oil temp switch, engine coolant temp switch, engine oil pressure switch and fuel pressure switch - none of these switches and the diagrams really look like what the switch is in question. The engine oil pressure switch looks like what's in the bottom right of the wider angled picture attached - I say 'looks like' because the diagram of switch/temperature locations doesn't have this switch in this location. I'm not sure if there's a gasket/oring to replace or just to replace the entire switch assembly. I have pondered this for a while now because I have a decent leak that is causing me about 1/2 gal of lube oil in 4 hours of running. It's also leaking onto my starter motor/solenoid which is a lesser problem, but i'd like to eliminate leaks if possible (especially ones like this). I tried tracing wires but they run almost immediately into the wiring harness and colors are impossible to trace anyway due to someone spraying the entire inside with yellow paint.
That's a oil pressure switch but it doesn't look like a cat switch cat number is 9g8010
I agree, and I have found that pressure switch under that part number. I just dont know what to replace or fix this switch with. It's also wired so I'm not sure what it is connected to. Hard to trace lines without cutting open the wiring harness.
Looks like the standard n/c Hobbs pressure switch. I've seen most of them running an hour meter.
See the illustration below. #17 is listed as "switch - engine oil pressure". Original Part Number 6T-7663 which appears to update to 107-0612. See attachment.
Vetech, good idea, maybe I'll try to disconnect a lead while at startup idle and see if the hour meter stops. I thought the hour meter was off one of the other oil pressure switches but maybe somehow it got changed. Nige, I did see that figure as well but what threw me off was the depiction of the pressure switch. The one in the drawing looks like the same one in the engine block to the bottom right of the one I'm questioning. I know it says cylinder head but that's what I was saying with some conflicting information. Would you say you have a relatively high level of confidence in that #17 pressure switch? Definitely appreciate the insight from you guys, this is great
Someone has replaced it at a previous repair and installed the wrong type of switch is my first thought. Maybe that's why the switch currently installed in the head is leaking.? The switch #1 lower down is actually listed as the 7N-9785 water temperature switch. Atlhough 6T-7663 and 7N-9785 look similar from the outside the guts of them are totally different.
Great information, Nige. I really appreciate it. When I first purchased the machine, the previous owner said he replaced the head and had a diesel mechanic reassemble everything. Seems very probable with your suggestion of the installation of an incorrect pressure switch. Also thanks for the additional information on the two different switches, as well as the attachment you provided a couple posts up. I feel more confident in what I want to do in the future. I will update this post (if I remember) with the results. Thanks again.
There are two oil pressure switches one for monitor and one for hour meter. The water temp sender will be on fan end of engine
According to the electrical schematic the power to the hour meter comes off the 403-GN wire which is the alternator warning light feed into the Monitor Panel.
I'll have to head to the machine and do some troubleshooting here in the next week. Ill try to verify and prove/disprove what I can to help with the issue. I called CAT just now and they provided me with the correct information for a new pressure switch. The information in the attachment you provided, Nige, was mostly correct and the guy I spoke to got me the switch specifically and said to go somewhere cheaper for the Deutsche connections. Great help. Switch should be here Monday.
Here's a question for you. From your earlier comments I take it you have a service manual. Does that manual include a paper fold-out version of the electrical schematic.? If so what is the Cat Publication reference on the front.? It will be something like SENRxxxx
Yes, I do have a service manual. The cat publication reference says SENR2033.
Is that for the electrical schematic or the whole manual.? The document reference on the schematic should be in the top RH corner just above the part containing the title.
Sorry, it was for the whole manual. Yes it does have a paper fold out version of the electrical schematic, in addition to a few other fold out pages. The electrical schematic in particular doesn't have a title on it, but in the lower right hand corner of both sheets is has a number. The first sheet says B12513X1 and the second sheet says B12514X1. The fold out pages are at the end of the volume 1 "systems operation testing and adjusting". If you're talking the front page, above the title, for that volume, it does have a form number that is labeled as SENR3193.
Right. Gotcha. It seems as though the electrical schematic was never previously published separately, only as part of SENR3193 in paper format.
Not really much of a schematic.Wiring in parts book had a lot more information back then HPCU only had one switch
Yeah, I agree with you. The schematic is relatively simple to follow, however, on my machine in particular (maybe others too, not sure) it's very hard to trace lines on the machine with them all being painted yellow for some reason. Plus, the wires don't seem to be traceable for very long due to them going directly to the wiring harness. I don't really want to cut it open to trace wires but might have to in the future. Dunno.
Do you have a parts book? Lot of times they will tell you wire color and what it connects to when you look at harness
You need a test light powered from battery+ connected to one end of a particular wire and a jumper cable to connect to machine frame ground at the other. If you're on the correct wire the test light will, well, light........... I'm sure you're right. Back in the day the wiring would have been a random page or two in the Parts Manual. I came across an electrical schematic that appears to be 3 pages (maybe from said Parts Manual or maybe from some random engineering drawings from a dusty archive stitched together in a single page. Big problem is that someone didn't line the wires up dead accurate when they did the stitching. However it's better than nothing. One good thing, the schematic does have wire numbers and colours marked on it, even though the document itself is not searchable like the modern ones are.
That electrical schematic you attached looks like it provides more detail than the one mine does, so maybe pittsburgh cat man is right with the parts book. I do not have a parts book, I've so far found that CAT's SIS online system is pretty good when trying to find most parts, so long as I can figure out what the component is identified as, hence why I haven't got a parts book yet (don't think SIS has electrical schematics though). And Nige, I do have a test light similar to what you're referring to, I think I just need to get more comfortable using it.
There schematic he attached is for a c model lots and lots of electric components Yours on the other hand has very few. Some of the attachments like air condition had a instruction that listed many machines that listed a lot of info by machine I think it had schematic listed by machine for the ac attachment. The switch you showed the picture of If it was me I would turn the master on turn jump the two wires on the sender I'm pretty sure it will turn on the hour meter or turn out the oil pressure light. As far as I can remember really old stuff the only thing the 403 wire from the ait does on your machine does is arm the alarm. One more question since your from pa your machine have a beckwith blue plate on it
According to the title page it is for a pre-B model, one with no suffix after the model number in other words.
Sorry, I am not sure what you're asking.
one of these we used to put them on every machine
As far as the schematic It is not a a or b model it has drive solenoids and a fuel gauge. Cat engineer told me once the people that did the books had no idea about the mechanics
Oh I see. No, my machine does not have that. I purchased my machine from a guy near cleveland.
Just providing an update. So I got the new switch from cat installed and the deutsche connections working good. Removal of the old switch was definitely a hobbs pressure switch like vetech mentioned. Ran the machine idle for a little just to test the switch. While running, I disconnected the deutsche connection and got the main warning light, the warning alarm sounded, and the oil light on the operator panel came on. The hour meter kept running so it wasn't tied to this switch. Based on my electrical schematic, this pressure switch isn't shown anywhere. The only ties that are supposed to be with oil pressure switches are with the switches labeled 9g8010. There is no information for the pressure switch I just replaced other than the figure with it in the head unit. So far so good, thanks for the discussion and information everyone.
Ive finally tracked down two of those. One on ebay and the other i had to buy a 931 to get it!
The switch in question looks to have an adapter that may be leaking as well.