7045 Wiring questions?
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Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=186367
Printed Date: 15 Sep 2025 at 6:18pm
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Topic: 7045 Wiring questions?
Posted By: Pete upstateNY
Subject: 7045 Wiring questions?
Date Posted: 10 Feb 2022 at 10:36pm
I have a 7045 with a serial number of 3792. I have wiring diagrams that I found in shop manuals. well I guess the only way to try and explain this is to add a picture. Be advised this is not my doing this is the way I purchased the tractor. I know it is in the oil pressure sending unit. But nowhere in any manual can I find a three wire oil pressure sending unit. Or how it was wired! Obviously I have the injection pump out |
Replies:
Posted By: Pete upstateNY
Date Posted: 10 Feb 2022 at 10:45pm
It does have a lift pump on it. In my limited mechanical knowledge I believe someone hardwired the lift pump to the key.
 Turn the key on lift pump starts running if I’m not mistaken the sending unit should be wired in and the lift pump should not start running until there is oil pressure. |
Posted By: Ron(AB)
Date Posted: 10 Feb 2022 at 11:53pm
|
I thought the lift pump should be running when the key is turned on so it helps to start the tractor...? Anyway, I would just put a two wire sending unit on which is normal for the tractor. ------------- 405, 7000, 7050, 8050, 8070, L3, 2300 & 2600 disk |
Posted By: Pete upstateNY
Date Posted: 11 Feb 2022 at 12:02am
| I guess the idea behind it not getting fuel right away is to pump oil to the top of the motor before the motor actually starts. Not my idea, an engineer that is way smarter than I am can take credit for that. I just want it to be put back to original and not cobbed up like the previous owner did. |
Posted By: DrAllis
Date Posted: 11 Feb 2022 at 5:13am
| Electric pump fired by the key. Oil pressure sender is ONE wire. |
Posted By: Tbone95
Date Posted: 11 Feb 2022 at 6:58am
|
Wouldn't think a lift pump would do that. . . .as in, develop enough pressure to literally bypass the flow and timing of the injector pump and pop the injectors with fuel enough to start the tractor "too early". It's just helping with the suction side because of the tanks being low. Just my opinion.
|
Posted By: Pete upstateNY
Date Posted: 11 Feb 2022 at 7:01am
| Thanks Doc.. I was hoping you or Mack would weigh in on this. So this is someone’s hair brain idea not an Allis design. Is the lift pump original to the tractor or did someone add that on also? |
Posted By: DrAllis
Date Posted: 11 Feb 2022 at 7:08am
| Later model 7000 series had that factory installed. Older models may have had it added on as a kit. |
Posted By: Pete upstateNY
Date Posted: 11 Feb 2022 at 7:16am
| OK awesome, thank you for the info. One more question didn’t they usually use a port more towards the back of the motor for the oil sending unit? I don’t think it matters I’m just trying to put it where it actually belongs. |
Posted By: DrAllis
Date Posted: 11 Feb 2022 at 7:24am
| in behind oil filter area as a rule. |
Posted By: MACK
Date Posted: 11 Feb 2022 at 7:31am
| A two or three wire pressure switch is usually for a gauge not a light. MACK |
Posted By: Pete upstateNY
Date Posted: 11 Feb 2022 at 7:40am
| did the 7045 come with a gauge option? Or was it just an on-off indicator light? |
Posted By: DrAllis
Date Posted: 11 Feb 2022 at 8:34am
| Never a gauge option. A red light was all. |
Posted By: Alvin M
Date Posted: 11 Feb 2022 at 9:20am
| AGCO part # is 74021445 one wire only back of oil filters |
Posted By: Adam Stratton
Date Posted: 11 Feb 2022 at 8:42pm
| 3 wire sending unit may have also been a safety "Murphy" switch at one point? I've been thinking of putting one in my 7000 that I use for auger work. Decent load and no one on the seat watching... The ones I've looked at are 3 wires. Some hot when oil pressure drops-warning light or I was thinking a horn in my application, some cold when it drops and could have that tied to a shut off somehow. |
Posted By: GM Guy
Date Posted: 12 Apr 2022 at 10:44pm
|
That sure looks like a sending unit off a combine. Any chance the motor
was swapped out of a combine? Depending on how much of a perfectionist
the swapper was, it either has a modded front plate to get the mounts or
they swapped the front plate. Also, that is a factory lift pump and mounting bracket, but they dont put them outside the framerail like that. the 1981 units were the only factory installed ones, all older it was a kit. framerail was notched slightly for the filter. all were on the inside. ------------- Gleaner: the properly engineered and built combine. If you need parts for your Gleaner, we are parting out A's through L2's, so we may be able to help. |