Source: My 1986 635CSI (Australia)
#1, Blue head (#7 on PD) = Coolant Temperature Sensor (CTS)
#2, Brown head (#9 on PD) = Temperature-Time Switch (TTS)
#3, White spades (#8 on the PD?) = Temperature sending unit/warning contact 120CEL
#4, Green w/ vacuum lines (#4 on PD) = Thermo-valve 45Cel
#1 Blue temp sensor is responsible for coolant temperature information to the computer for proper engine performance.
#2 Brown thermo-time switch is responsible for cold start valve operation, it reads the coolant temperature and if it's low enough then the cold start valve will fire.
#3 White 2-pin temp sensor is responsible for coolant temperature indication on cluster
#4 Green thermo-valve is responsible for idle control valve function.
Parts Diagram
Part Numbers:
(reference link):
#1, Blue head (#7 on PD) = Coolant Temperature Sensor (CTS)
13621709967
Supersedes: 13621709966, 13621284397
#2, Brown head (#9 on PD) = Temperature-Time Switch (TTS)
13621362599 (Electronic switch)
Supersedes: 13621274630 (Bi-metal switch, NLA)
#3, White spades (#8 on the PD) = Temperature sending unit/warning contact 120CEL
62161360870
#4, Green w/ vacuum lines (#4 on PD) = Thermo-valve 45Cel
11741264132 - Same part used in the Volume / Mass Airflow Sensor (MAF) area.
Supersedes: 11741264134
Troubleshooting articles:
Thermo Time Switch (TTS) Testing and Calibration (BimmerForums)
Internet Archive Link for posterity (TBC)
Thermo time switch unplugged - Cranks but no start? (BimmerForums)
Internet Archive Link for posterity (TBC)
Ted's House BMW e30 Idle FAQ - An excellent, Cold Start, Hot Start Troubleshooting guide.
Note: I understand that newer E24s (>1983?) do not have a separate Idle Control Module. the ICM is now built into the ECU.
Internet Archive Link for posterity (TBC)
Thermostat Housing Temperature Sensors - What do they do?
Moderators: GRNSHRK, ron, bfons
Thermostat Housing Temperature Sensors - What do they do?
Last edited by TimU on Wed Jun 14, 2023 12:55 am, edited 7 times in total.
04/1986 635csi Euro spec
Australian Delivered, RHD
Australian Delivered, RHD
- 86_6series
- Platinum Member
- Posts: 1069
- Joined: Mon Apr 02, 2007 10:08 pm
- Location: West Nyack, NY
Re: Thermostat Housing Temperature Sensors - What do they do?
Search the part #'s to get what they are for, https://eeuroparts.com/, usually has a description.
86-635CSi
96-MB C220 SOLD
98-740i
71-Continental MK3
96-MB C220 SOLD
98-740i
71-Continental MK3
Re: Thermostat Housing Temperature Sensors - What do they do?
Thanks - Yes, I have.86_6series wrote: ↑Wed Apr 13, 2022 12:12 pm Search the part #'s to get what they are for, https://eeuroparts.com/, usually has a description.
My post above was trying to consolidate everything into a single location for personal and future reference.
Just seeking to cross-check my understanding with those more knowledgable about these things.
I have updated my OP with part numbers and some extra troubleshooting guides I found useful.
04/1986 635csi Euro spec
Australian Delivered, RHD
Australian Delivered, RHD
Re: Thermostat Housing Temperature Sensors - What do they do?
'85 635csi JPS (RA2-66)
- 86_6series
- Platinum Member
- Posts: 1069
- Joined: Mon Apr 02, 2007 10:08 pm
- Location: West Nyack, NY
Re: Thermostat Housing Temperature Sensors - What do they do?
Just realized that when I posted you were in the middle of searching, great minds or what? (LOL)
86-635CSi
96-MB C220 SOLD
98-740i
71-Continental MK3
96-MB C220 SOLD
98-740i
71-Continental MK3
Re: Thermostat Housing Temperature Sensors - What do they do?
Thanks, but that looks completely different to mine.
04/1986 635csi Euro spec
Australian Delivered, RHD
Australian Delivered, RHD
Re: Thermostat Housing Temperature Sensors - What do they do?
For anyone stumbling across this post in the future, here is what the sensors and switches look like when they've been pulled out.
04/1986 635csi Euro spec
Australian Delivered, RHD
Australian Delivered, RHD