usrjcro11 Posted February 5, 2022 Share Posted February 5, 2022 just bot this truck and trying to learn. Printed owners manual off and reading. The override switch on this truck does not stay engage when pushed up. It rocks down when released is this normal? Read on this forum about checking ground on vmac and ecm behind kick panel on passenger side. Startied trying to take bolts out but they just turn but not come out. Does this mean they are stripped?i I tried finding the bmt post about the grounds behind panel again but could not Am I correct their are grounds behind panel. The pyrometer gauge is not registering so I wanted to start eliminating all grounds first.Thanks Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted February 5, 2022 Share Posted February 5, 2022 the override switch is a momentary switch, to stop engine shut down due to low coolant warning, and other issues that i cant remember. behind the kick panel would be the VECU and FIC module if your injection pump is a Robert Bosch with an electric governor housing. the screws should be T-27 torx and yes can be stripped. they screw into speed nuts.. drill them out and start over. there are grounds behind the cluster and near the fuse panel behind the cover on the right side dash. There is also a ground on the frame behind the left steer tire, and at the engine block in front of the starter, and on the firewall there should be a ground breaker, bolted next to the starter relay. it's all black and is only a grounder. also when you turn the key on you should hear a loud click, that is the accessory relay in the dash, its behind the center panel, make sure all of the contacts are clean and tight... that should do it... go to the kick panel last. just because... jojo Quote Link to comment Share on other sites More sharing options...
usrjcro11 Posted February 5, 2022 Author Share Posted February 5, 2022 The injection pump has plug of wires going to it Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted February 5, 2022 Share Posted February 5, 2022 what is the issue that you are having? Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted February 5, 2022 Share Posted February 5, 2022 remove the pyrometer, and hold a lighter to it to check the gauge operation. no need to run the engine. jojo 1 1 Quote Link to comment Share on other sites More sharing options...
usrjcro11 Posted February 5, 2022 Author Share Posted February 5, 2022 I unplugged the electrical plug by radiator that has air hose going from it to fan. I had read on here when unplugged fan should run. It did not. After further investigating before dark water temperature sensor had white wire going to it traced back to a cab toggle switch previous owner had installed. Cut switch on and fan comes on. When I drove truck on the pyrometer gauge did not move. Only gauges moved was oil and water temp. No movement of transmission or rearends. I had posted this before and somebody said to sensors with lighter. Thinking aloud that maybe have ground issue. Just learning. Quote Link to comment Share on other sites More sharing options...
usrjcro11 Posted February 5, 2022 Author Share Posted February 5, 2022 Here is picture of auxiliary wire that goes to toggle switch in cab Quote Link to comment Share on other sites More sharing options...
usrjcro11 Posted February 7, 2022 Author Share Posted February 7, 2022 I traced wires from temp sensor to toggle switch. The other side of toggle switch goes to ground. So when you toggle switch up it sends ground to the sensor and the fan locks in and turns. The wire on sensor has 12 volts on it when toggle switch is off. Trying to figure out what I need to do to make fan come on automatically and not by toggle switch. Thanks. Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted February 7, 2022 Share Posted February 7, 2022 the control valve on the radiator frame uses 12 volts to unlock the fan ( air pressure needs to be above 90). when you take power away, and air pressure is up, the fan will lock. The fan control valve have 3 ports for air. 1 is air 'in' another is air 'out' and the other is exhaust. a black knurled looking knob. I believe air goes in the top, out the bottom to the fan, down to the bottom of the fan shroud, then up to the fan clutch. The valve has 2 positons for plumbing. 'normally open' and 'normally closed' is it installed correctly? I will try to find the wire diagram for youre older CH. for some reason I dont recall the sensor in the front manifold. I always see 2 sensors in the rear manifold, one facing the firewall and one on the side facing left. I'm curious about the wiring at the rear of the engine, as to what wires were cut or changed... jojo Quote Link to comment Share on other sites More sharing options...
usrjcro11 Posted February 7, 2022 Author Share Posted February 7, 2022 The wiring diagram in fuse cover shows one wire going to sensor and one wire going to control valve on radiator frame. One wire on both these going to ground.Both of these connectors are two wire connectors. The two wires are 1 12 volts and 1 ground. I did not see any cut and spliced wires on wireimg harness. Only the additional wire going to toggle switch in cab. Mr.joey MACK are you suggesting wires maybe wrong or the airlines going to control valve. Are the lines going to air valve push in type? I will get picture of valve tomorrow. Can the knurled knob turn to change settings? Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted February 7, 2022 Share Posted February 7, 2022 the knurled knob is exh. it unscrews. in rare cases I have seen them plumbed wrong. i beleive, that when you switch the supply line with the exh. port, you change the way the switch operates. usually the exh. port is in the side port, and supply in the top, delivery to the fan out the bottom. jojo 1 Quote Link to comment Share on other sites More sharing options...
usrjcro11 Posted February 7, 2022 Author Share Posted February 7, 2022 This is picture of control valve for fan by radiator Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted February 7, 2022 Share Posted February 7, 2022 looks like the exh. is at the top.. try swapping the exh fitting with the fitting in the side port. then test it, you can put shop air to the truck, and cycle the key to get air to flow.. jojo Quote Link to comment Share on other sites More sharing options...
usrjcro11 Posted February 8, 2022 Author Share Posted February 8, 2022 I can put shop air to tanks. You want me to swap air lines and cut key on and see if air comes out exhaust or fan locks up. I am confused sorry. Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted February 8, 2022 Share Posted February 8, 2022 both.. when you cut the key off, in a few seconds the fan should lock, if its plumbed right. air pressure locks it.. hooking shop air keeps you from running it up to temp to see if the celenoid works.. Im sorry about being confusing.. jojo Quote Link to comment Share on other sites More sharing options...
usrjcro11 Posted February 8, 2022 Author Share Posted February 8, 2022 Will test in morning Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted February 8, 2022 Share Posted February 8, 2022 be sure to dissconnect the home made wire at the sensor, leaving the truck wires attached.. good luck jojo Quote Link to comment Share on other sites More sharing options...
JoeH Posted February 8, 2022 Share Posted February 8, 2022 Pyro gauges stick sometimes. With the engine up to temp driving around, tap the face of the gauge. One of my trucks does that. Quote Link to comment Share on other sites More sharing options...
usrjcro11 Posted February 8, 2022 Author Share Posted February 8, 2022 Swapped lines with air on tanks. It Activated pop off on top of solenoid. Fan did not lock. Control valve switch has 12 volts on one side and no ground on other side. This wire with no ground traces to one side of sensor. Fan does not lock with air on tanks with key off or key on. i was thinking fan free wheels till sensor closes when hot then goes to ground sending ground to control valve on radiator to lock fan Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted February 8, 2022 Share Posted February 8, 2022 Is air pressure present at the 1/4" line going in to the celenoid for the fan ? Quote Link to comment Share on other sites More sharing options...
usrjcro11 Posted February 9, 2022 Author Share Posted February 9, 2022 To make sure we are talking about same thing. The celenoid for fan is the unit I took picture of. It does have air going to it. I do not understand how when you cut key off the fan will lock. Where is it getting power and ground with key off to activate it. I see on wiring diagram it show engine water temperature sending unit going to dash gauge. The gauge has wire 17e08 going to one side of sensor and other side going to ground. My schematic does not show celenoid to control fan lockup. It does show a kysor dynair fan clutch air solenoid with only one wire going to it which is bkl08 which goes to ground on sheet 2 but it also says see sheet 5 for Horton dynair fan on sheet 1. I do not have sheet 5. i also see what is called water temperature sensor with wire going to Bosch module ms3 which is different from engine water temperature sending unit. i do not want to sound contrary. I am just trying to understand how it suppose to work. Understanding the problem is 90 percent of solving problem. Quote Link to comment Share on other sites More sharing options...
mechohaulic Posted February 9, 2022 Share Posted February 9, 2022 the question i was thinking was-- what fan hub model are you working on ? the older hortons would use air pressure to DISENGAGE the fan. reason being if the system had a problem it's better to have a fan stuck on then one not engaging. the added wire may have been installed to put fan on before temp. an owner operator had a switch in dash for manual fan so he could engage fan before a hill and not have fan kick in half way up . or could be half -ass way to not fix a problem. have seen many of those "mechanics" ; don't fix it just run anew wire guys. Quote Link to comment Share on other sites More sharing options...
Vmac3 Posted February 9, 2022 Share Posted February 9, 2022 Try supplying air pressure directly to the fan air supply and see what happens. Most times the friction material on the clutch wears out. mechohaulic is correct saying that the air solenoid energizes to supply air to engage the fan clutch, this is a fail safe when it loses power or ground. I will also try and dig up a wiring diagram. V Quote Link to comment Share on other sites More sharing options...
Vmac3 Posted February 9, 2022 Share Posted February 9, 2022 On 2/5/2022 at 11:18 AM, usrjcro11 said: Here is picture of auxiliary wire that goes to toggle switch in cab That is a switch that is normally open or closed. When the water temp reaches a certain value then it opens or closes to supply a ground or removing it These were usually to control fan clutch operation as mentioned before. Also there is a 135A ground circuit breaker by the wiper motor, make sure it is clean and nor corrosion. V Quote Link to comment Share on other sites More sharing options...
usrjcro11 Posted February 14, 2022 Author Share Posted February 14, 2022 Removed sensor and put propane torch on it. Did not like how long it took for it to lock fan. Got a new 200 degree lockup sensor. That was the lowest degree available. Thanks all. Quote Link to comment Share on other sites More sharing options...
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