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140h grader no voltage on the transmission solenoids

servas

New Member
Joined
Feb 14, 2016
Messages
3
Location
Malawi
Cat grader 140H, Engine # 3306, Serial #6NCO6158#1464337, Transmission #4MYO411#1442234, has got a transmission problem! I need your help, you, experienced technicians, please! It all started with the parking brake clutches. This happened when the operator drove the grader with inadequate air pressure in the brake system, hence, the parking clutches in the transmission got burnt. We remove the burnt clutches and fitted new ones. Assembled the transmission and when we started the grader only 1 forward and reverse gears operated. I checked the voltage on the solenoid D and G for parking and neutral, there was no voltage at all. The manual says when the shift lever is on park or neutral voltage (24v) should be found on these solenoids. when the shift lever is on gear 1 forward or reverse, voltage is found on the solenoids for that gear, but when you put into 2 forward to 8 gears or 2 reverse to 6 gears, voltage is found on solenoids D and G, in other words the ECM is neutralizing the transmission. EMS displays a transmission fault warning light. I swapped the ECM but the same is happening, I checked the harness from the ECM to the solenoids, just fine, harness from the ECM to the Shift lever and also it is good. what can be really the problem with this transmission? the transmission warning light came after assembling the transmission. These problems came when we dismantled the transmission, but before that it was just fine. please, I humbly ask your help!
 

Cmark

Senior Member
Joined
Jan 2, 2009
Messages
3,176
Location
Australia
Did you replace the parking brake discs in-situ or did you remove the entire transmission? If you removed the entire transmission, then you have to assume you got something wrong when you reconnected the wiring.

From memory, I think there's a couple of 2 pin deutsch plugs that you can get wrong. Output speed sensor and oil pressure maybe? What fault codes do you have?
 

servas

New Member
Joined
Feb 14, 2016
Messages
3
Location
Malawi
We removed the entire transmission. We didn't disconnect those 2 pin deutsch plugs for we disconnected the connector above the transmission solenoids which have got 4 cables, 2 for speed sensor and the other 2 for transmission temperature. we connected the transmission solenoids connectors in reference to the manual. Thanks.
 

servas

New Member
Joined
Feb 14, 2016
Messages
3
Location
Malawi
transmission serial number is #4MYO411#1442234 according to plate mounted on the steering near the fuse box. Thanks
 

mrappels

Well-Known Member
Joined
Nov 30, 2015
Messages
60
Location
Australia
Occupation
Diesel Plant Fitter
may i suggest checking your modulting valves if you dont have access to an ET. dont quite understand it, but lost power to the solenoids beyond a certain gear, think it was 3rd.. anyway, may i suggest checking the resistances on your clutch solenoids before removing the transmission, just in case. maybe one was damaged during removal/installation..
 

umar

Member
Joined
Apr 28, 2020
Messages
9
Location
nigeria
Hi anyone still here? I am having same issue as above but my 140H grader solenoid valve gives 4.6 Volts yet working normal, but I thought it was suppose to deliver 24Volts when tested with a multi meter? Pls someone help
 

umar

Member
Joined
Apr 28, 2020
Messages
9
Location
nigeria
The gears were actually not responsive before so we changed the solenoids for all the gears and they were now responding on the coil body it was indicated that it was a 24V solenoid I also used a direct battery to actuate it but on installation on machine the voltage read 4.6V for all the 5 speed and 3 directional solenoids, am afraid hope the voltage is not small and won't get damaged costing me more money, though the resistance shows between 30.9-31 ohms which I see is okay . Thanks
 

mrappels

Well-Known Member
Joined
Nov 30, 2015
Messages
60
Location
Australia
Occupation
Diesel Plant Fitter
I'll have to read up on it but I'm pretty sure that these solenoids are pulse width modulated for a smooth clutch engagement.
When the ecm detects a fault, (such as disconnecting a solenoid plug to check voltage) it limits the output voltage to 5 volts and stops any current flow. If you have the old solenoids you should find that one or two are suspect, seeing as changing them all has fixed the problem. For ease of mind, you should set the machine up and do a pressure check on the clutches to ensure your clutch combinations are engaging as they should. Remember that it needs to have all the wheels off of the ground/removed in order to do this.
 

umar

Member
Joined
Apr 28, 2020
Messages
9
Location
nigeria
I'll have to read up on it but I'm pretty sure that these solenoids are pulse width modulated for a smooth clutch engagement.
When the ecm detects a fault, (such as disconnecting a solenoid plug to check voltage) it limits the output voltage to 5 volts and stops any current flow. If you have the old solenoids you should find that one or two are suspect, seeing as changing them all has fixed the problem. For ease of mind, you should set the machine up and do a pressure check on the clutches to ensure your clutch combinations are engaging as they should. Remember that it needs to have all the wheels off of the ground/removed in order to do this.
I have done all this and all was working perfectly well as at the time, yet the machine was returned back to the workshop that all gears not engaging, I tried cleaning the spools again by opening the valves from the back and replacing them one after the other while testing again, at the time I engaged the reverse and operated the machine at high idle I heard a bop sound and the machine went off, upon restarting all reverse gear engaged perfectly, but forward still won't engage, I decided to service entirely the Transmission control valve which hopefully I would mount back today, replace the trans oil and also the filter and try again, I don't see any errors on ET, but would I be needing to calibrate the Trans control valves after servicing it?
 

Nige

Senior Member
Joined
Jun 22, 2011
Messages
28,979
Location
G..G..G..Granville.........!! Fetch your cloth.
If you have been moving clutch solenoid valves around from one location to another on the transmission control valve I would say that a re-calibration would be necessary. If you have not replaced any solenoid valves and they are all in their original locations then strictly speaking no, but it would not hurt to do a re-calibration anyway provided you have the resources to do it.
 
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