Re: [MBZ] fan temp sensor W124 OM602
On Sun, 15 Mar 2020 18:49:24 -0400 Meade Dillon via Mercedes wrote: > Curley - found a clean copy of your wiring diagram. Thank you, Max. That is cleaner than the one I have. > Check out this page on Benzworld for nice clean copies of all the 124 > ETM. > > Scroll down to thread #7. > > https://www.benzworld.org/threads/anyone-hosting-supplement-14.1506315/ I will have to check them out. Craig ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] fan temp sensor W124 OM602
On Sat, 14 Mar 2020 23:34:00 -0500 Curley McLain via Mercedes wrote: > I read on a PP forum that unplugging a relay and pluggin it in cured a > problem (Seat adjustment not working, both front seats) Maybe it is > not unusual tha tpulling the relay and putting it back in cured the > problem. Did you use contact cleaner when you put the relay back in? Craig ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] fan temp sensor W124 OM602
Just get deoxit on the pins and work them in and out. Greg -Original Message- From: Mercedes [mailto:mercedes-boun...@okiebenz.com] On Behalf Of Curley McLain via Mercedes Sent: Sunday, March 15, 2020 6:45 AM To: Meade Dillon via Mercedes Cc: Curley McLain Subject: Re: [MBZ] fan temp sensor W124 OM602 Yesterday the low speed worked when I pulled and replaced the relay k10, with the top sensor pulled and the pressure switch by the dryer jumped. But then it quit again on the test drive. I replaced the relay with one I stole from the SDL, but have not driven it yet. It worked in the same static test, pulling and replacing the relay. I suppose I should dig out the deoxit and spray the pins and sockets, but it is not i n an easy place to get to. I still don't know if the pins were not making contact, if the relay is intermittent or if the wires connecting to the relay socket are flakey. I think one of the first two, or a combination. I guess it makes sense that disconnecting the top sensor activates a fail safe. that would explain the action of the sensor running counter to observed activity. Wish these cars had manual h-A/C controls! I still despise ACC in any number. To me, engine heat management belongs in the cooling section, not in ACC section. It is a critical component of engine operation. The cooling section should at least have references to where they buried the engine heat management stuff. Did I ever mention I don't like ACC? Meade Dillon via Mercedes wrote on 3/15/20 6:37 AM: > Read FSM 83-600, sections I thru K. That explains how the aux fan circuits > function. The high speed is controlled via the HVAC PBU; I suspect that > when you disconnect that temperature sensor, the HVAC has a circuit which > defaults to turning the fans on (emergency fail-safe). In other words, the > PBU will turn on the fans if the temperature sensor gives a high > temperature reading (looks like 107 deg C) OR the PBU will turn on the fans > if there is an open circuit and it doesn't know what the engine temperature > is. > > Did you verify that the low speed side is working correctly? > - > Max > Charleston SC > > ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] fan temp sensor W124 OM602
Yesterday the low speed worked when I pulled and replaced the relay k10, with the top sensor pulled and the pressure switch by the dryer jumped. But then it quit again on the test drive. I replaced the relay with one I stole from the SDL, but have not driven it yet. It worked in the same static test, pulling and replacing the relay. I suppose I should dig out the deoxit and spray the pins and sockets, but it is not i n an easy place to get to. I still don't know if the pins were not making contact, if the relay is intermittent or if the wires connecting to the relay socket are flakey. I think one of the first two, or a combination. I guess it makes sense that disconnecting the top sensor activates a fail safe. that would explain the action of the sensor running counter to observed activity. Wish these cars had manual h-A/C controls! I still despise ACC in any number. To me, engine heat management belongs in the cooling section, not in ACC section. It is a critical component of engine operation. The cooling section should at least have references to where they buried the engine heat management stuff. Did I ever mention I don't like ACC? Meade Dillon via Mercedes wrote on 3/15/20 6:37 AM: Read FSM 83-600, sections I thru K. That explains how the aux fan circuits function. The high speed is controlled via the HVAC PBU; I suspect that when you disconnect that temperature sensor, the HVAC has a circuit which defaults to turning the fans on (emergency fail-safe). In other words, the PBU will turn on the fans if the temperature sensor gives a high temperature reading (looks like 107 deg C) OR the PBU will turn on the fans if there is an open circuit and it doesn't know what the engine temperature is. Did you verify that the low speed side is working correctly? - Max Charleston SC ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] fan temp sensor W124 OM602
Read FSM 83-600, sections I thru K. That explains how the aux fan circuits function. The high speed is controlled via the HVAC PBU; I suspect that when you disconnect that temperature sensor, the HVAC has a circuit which defaults to turning the fans on (emergency fail-safe). In other words, the PBU will turn on the fans if the temperature sensor gives a high temperature reading (looks like 107 deg C) OR the PBU will turn on the fans if there is an open circuit and it doesn't know what the engine temperature is. Did you verify that the low speed side is working correctly? - Max Charleston SC On Sat, Mar 14, 2020 at 11:24 PM Curley McLain via Mercedes < mercedes@okiebenz.com> wrote: > with cold engine, the fan temp sensor at the top front of the head has > 5,000 ohm resistance. At 80 to 82ºC coolant temp, it is 600 ohms. > > One wire is at 5v. (From terminal 8 of the ACC PBU.) The other goes to > ground. via ACC air delivery (whatever that is) > > > At infinity ohms (plug unhooked,) the fans will come on with the key on. > > So if the fans come on at higher resistance, the would seem that the > resistance should get higher as the temp gets warmer. Instead, the > resistance gets lower as the temp gets higher. > > I am so far, not convinced that the sensor is good or is bad. It is > still suspect because I don't know what the specs are for its performance. > > > ___ > http://www.okiebenz.com > > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com > > ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] fan temp sensor W124 OM602
Craig via Mercedes wrote on 3/14/20 10:57 PM: On Sat, 14 Mar 2020 22:23:35 -0500 Curley McLain via Mercedes wrote: So if the fans come on at higher resistance, the would seem that the resistance should get higher as the temp gets warmer. Instead, the resistance gets lower as the temp gets higher. I am so far, not convinced that the sensor is good or is bad. It is still suspect because I don't know what the specs are for its performance. To what does the sensor connect? In the text: One wire is at 5v. (From terminal 8 of the ACC PBU.) The other goes to ground. via ACC air delivery (whatever that is) Is there a module which could be malfunctioning? Yes. ACC pushbutton, ACC Air delivery (whatever that is) I read on a PP forum that unplugging a relay and pluggin it in cured a problem (Seat adjustment not working, both front seats) Maybe it is not unusual tha tpulling the relay and putting it back in cured the problem. Craig ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] fan temp sensor W124 OM602
On Sat, 14 Mar 2020 22:23:35 -0500 Curley McLain via Mercedes wrote: > So if the fans come on at higher resistance, the would seem that the > resistance should get higher as the temp gets warmer. Instead, the > resistance gets lower as the temp gets higher. > > I am so far, not convinced that the sensor is good or is bad. It is > still suspect because I don't know what the specs are for its > performance. To what does the sensor connect? Is there a module which could be malfunctioning? Craig ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
[MBZ] fan temp sensor W124 OM602
with cold engine, the fan temp sensor at the top front of the head has 5,000 ohm resistance. At 80 to 82ºC coolant temp, it is 600 ohms. One wire is at 5v. (From terminal 8 of the ACC PBU.) The other goes to ground. via ACC air delivery (whatever that is) At infinity ohms (plug unhooked,) the fans will come on with the key on. So if the fans come on at higher resistance, the would seem that the resistance should get higher as the temp gets warmer. Instead, the resistance gets lower as the temp gets higher. I am so far, not convinced that the sensor is good or is bad. It is still suspect because I don't know what the specs are for its performance. ___ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
