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View Full Version : How Can I Scan the Charge Temp Sensor??



nomadman2001
08-27-2006, 07:48 PM
Just installed a charge temp sensor - running Rob's 2.5 +40 custom cal - and I can't "see" it with my scan tool (OTC 4000 Enhanced). Inmyshadow and I tried selecting various different body/engine combos but never seemed to hit the right one. Has anyone had success here?
Thanks, Jim.

ShelGame
08-27-2006, 08:30 PM
No current scan tool can see the charge temp sensor on the '89 T1. The charge temp sensor doesn't even have a routine (like the coolant temp sensor does) to send the data to the scantool.

It's possible to reprogram the SMEC to show the coolant temp sensor instead, but that's about as close as you're going to get - for now :)

turbovanmanČ
08-27-2006, 08:42 PM
Yep, use the 88, 89 or 90 routine and plug in code A. It will also ask for you ECM $!#$#$#@ as well. Just play around until you see it and the data looks real. If you pick the one wrong, your data is totally out.

nomadman2001
08-27-2006, 09:22 PM
No current scan tool can see the charge temp sensor on the '89 T1. The charge temp sensor doesn't even have a routine (like the coolant temp sensor does) to send the data to the scantool.

It's possible to reprogram the SMEC to show the coolant temp sensor instead, but that's about as close as you're going to get - for now :)
Are you saying it's possible to 'swap' signal input from the coolant sensor to the charge temp sensor and 'see' the charge temp under the coolant temp title?

ShelGame
08-27-2006, 09:24 PM
Are you saying it's possible to 'swap' signal input from the coolant sensor to the charge temp sensor and 'see' the charge temp under the coolant temp title?

Exactly. But, then you wouldn't be able to read coolant temp.

In my experience, the charge temp sensor doesn't really change much. It really follows the manifold metal temperature more than the actual charge temp...

nomadman2001
08-27-2006, 10:04 PM
I just installed it and was wondering if there is any way to check to verify it works - does't throw code if I unplug it so how do I know it operates 'correctly'?
Also, my sensor is all plastic, I understand those have a better ability of isolating the manifold temp from the actual air temp.

turbovanmanČ
08-28-2006, 01:26 AM
Its supposed to throw a code if you unplug it. If it doesn't, its not turned on. The plastic ones are the newer style and won't interchange with the older metal ones due to connector differences.

Directconnection
08-28-2006, 12:39 PM
my '90 vnt gives me degrees... my fireind's '89 T-II give me cts in volts so you'd need to convert if memory serves me correctly.

turbovanmanČ
08-28-2006, 12:54 PM
my '90 vnt gives me degrees... my fireind's '89 T-II give me cts in volts so you'd need to convert if memory serves me correctly.

Correct, the CAT is in volts. I'll see if I can dig up the chart I made for Dbltrbl.

MiniMopar
08-28-2006, 02:50 PM
The original factory CAT and coolant sensors on our 87s were grey plastic. The CAT always got cooked on the early T1s and had to be replaced every few years. The aftermarket sensors tend to be brass...cheaper for them since the thermistor is the same and all they have to do is machine the tip differently and glue a different connector on.

I think Simon is talking about the CAT connector that changed in 89 or 90. You can dremel the plug a bit and it will fit. I think the old one had one side curved and had a single key and the new one is square on both sides and had a key on each edge. Cindy also sells the CAT pigtail, which is the newer connector.

nomadman2001
08-28-2006, 07:10 PM
Its supposed to throw a code if you unplug it. If it doesn't, its not turned on. The plastic ones are the newer style and won't interchange with the older metal ones due to connector differences.
I know the CEL didn't come on when I unplugged it - don't remember if I checked codes after or not as I was going through so many eng configs on the scanner to try and find one that would read it :yuck: .
The sensor came with a manifold I bought used and I searched through my old harnesses until I found the right connector for it - didn't know about any other config sensor. I tied one side to pin 21 on the 60 SMEC conn'r and the other side to the LB-BK Sensor Ground wire on the TPS.
Seems odd that if it's enabled and unplugged, defective or not wired right, that it doesn't throw a CEL.....:confused:

nomadman2001
08-29-2006, 10:02 AM
Yep, use the 88, 89 or 90 routine and plug in code A. It will also ask for you ECM $!#$#$#@ as well. Just play around until you see it and the data looks real. If you pick the one wrong, your data is totally out.
Can't use 90 (SBEC) because all the data is stored in different locations in the code - tried it and all the data is skewed - does show a catagory for CHG-T though. Can't use ENG A in 88 or 89 because it doesn't recognize the data stream - it thinks the key is still off.
Checked for fault codes and it DOES show code 23! So I do have a problem ......I will start troubleshooting that next. I have confirmed my wiring - Pin 21 TB Sensor on the 60 pin connector and Sensor Ground Pin 4 to the 60.
I'll ohm it out and see if it's open/shorted since I can't find a resistance spec at ambient temp.
BTW, I'm looking for a cliff to push the car off of.......anyone know a good high one :eyebrows: .

ShelGame
08-29-2006, 10:56 AM
Can't use 90 (SBEC) because all the data is stored in different locations in the code - tried it and all the data is skewed - does show a catagory for CHG-T though. Can't use ENG A in 88 or 89 because it doesn't recognize the data stream - it thinks the key is still off.
Checked for fault codes and it DOES show code 23! So I do have a problem ......I will start troubleshooting that next. I have confirmed my wiring - Pin 21 TB Sensor on the 60 pin connector and Sensor Ground Pin 4 to the 60.
I'll ohm it out and see if it's open/shorted since I can't find a resistance spec at ambient temp.
BTW, I'm looking for a cliff to push the car off of.......anyone know a good high one :eyebrows: .

Right, the T2 uses different routines for the scantool than the T1. Not to mention different addresses, etc.

If you're using D-Cal, you can re-route the coolant temp to show the charge temp instead - Make a new 8-bit constant at #9908h, the value will be #6Ah (the address for the coolant temp), change it to #5F (the address for charge temp volts). The only other probelm is, the charge temp is not scaled internally in the SMEC, so the scantool display will show Deg F, but you have to ignore that. The outut value will basically be useless. At least, you'll be able to see if the sensor is working.

Even better - does your scantool have an option to show raw coolant temp volts? If so, then use #9909h for the constant address instead (value will be #6Eh). That's the coolant temp volts ouput. Change it to #5Fh and your display will be correct. Plus, you'll still have your coolant temp...

nomadman2001
08-29-2006, 12:32 PM
You're awesome Rob! Thanks. Right now I don't think it works because I'm getting a code 23. Once I get that resolved I'll give it a try.


Right, the T2 uses different routines for the scantool than the T1. Not to mention different addresses, etc.

If you're using D-Cal, you can re-route the coolant temp to show the charge temp instead - Make a new 8-bit constant at #9908h, the value will be #6Ah (the address for the coolant temp), change it to #5F (the address for charge temp volts). The only other probelm is, the charge temp is not scaled internally in the SMEC, so the scantool display will show Deg F, but you have to ignore that. The outut value will basically be useless. At least, you'll be able to see if the sensor is working.

Even better - does your scantool have an option to show raw coolant temp volts? If so, then use #9909h for the constant address instead (value will be #6Eh). That's the coolant temp volts ouput. Change it to #5Fh and your display will be correct. Plus, you'll still have your coolant temp...

turbovanmanČ
08-30-2006, 01:46 AM
Sorry about the 90 but it was so you get the idea. Weird, I use the scanner, punch in 89 and put in engine code A. I get the Cat voltage on my van.

nomadman2001
08-30-2006, 07:18 AM
Sorry about the 90 but it was so you get the idea. Weird, I use the scanner, punch in 89 and put in engine code A. I get the Cat voltage on my van.
No prob;em .............. Interesting Simon that you can use code A - when I try yhat it acts like the key is still off. I have an OTC 4000 Enhanced - what scantool do you use?
Jim.

ShelGame
08-30-2006, 08:57 AM
Sorry about the 90 but it was so you get the idea. Weird, I use the scanner, punch in 89 and put in engine code A. I get the Cat voltage on my van.

On the TU cal? Or my cal?

nomadman2001
08-30-2006, 12:20 PM
Even better - does your scantool have an option to show raw coolant temp volts? If so, then use #9909h for the constant address instead (value will be #6Eh). That's the coolant temp volts ouput. Change it to #5Fh and your display will be correct. Plus, you'll still have your coolant temp...
Yes it does, I'll give it a try. I just finished de-pinning the entire 60 way conn'r to ohm out the wires and clean the contacts. Everything was < .5 ohms but the contacts looked cruddy so I cleaned them up. Goin out now for a blast to see what happens :D .
BTW, the code I had for the CTS must have been an old one while I was playing around - seems to work fine now - no code until I unplug it - then 23, re-connect / clear code and all is normal.
One day I'll have this ironed out :nod: .
Jim.

turbovanmanČ
08-30-2006, 04:25 PM
No prob;em .............. Interesting Simon that you can use code A - when I try yhat it acts like the key is still off. I have an OTC 4000 Enhanced - what scantool do you use?
Jim.

Snap On and the OTC Enhanced.




On the TU cal? Or my cal?

TU cal and if memory serves, your cal too. I will double check and post my results.

ShelGame
08-30-2006, 04:50 PM
TU cal and if memory serves, your cal too. I will double check and post my results.

Hmm, that shouldn't work. The T2 (A Code) and the T1 use a completely different routine and command structure for the scantool data...

nomadman2001
08-31-2006, 08:58 AM
Hmm, that shouldn't work. The T2 (A Code) and the T1 use a completely different routine and command structure for the scantool data...
Right, Code A won't read any data for me - acts as if the key is still turned off.
My sensor works OK - test drove it yesterday - 22 PSI boost and no codes :D . Still ironing out the Advance & Fuel Curves - but that's another subject :nod: .

ShelGame
08-31-2006, 09:12 AM
Right, Code A won't read any data for me - acts as if the key is still turned off.
My sensor works OK - test drove it yesterday - 22 PSI boost and no codes :D . Still ironing out the Advance & Fuel Curves - but that's another subject :nod: .

The bait and switch with the coolant temp volts/charge temp volts worked OK then?

nomadman2001
08-31-2006, 01:58 PM
The bait and switch with the coolant temp volts/charge temp volts worked OK then?
I have not gotten there yet ....... I know the CTS works because it will throw a code if I disconnect it (no CEL, just code 23) and will not come back once reconnected and code cleared. I'm ironing out the (your) cal since getting the motor and trans back in the car. Oddly enough, I'm running the 2.2 custom cal form d-cal because the fuel curves lined up almost perfectly with where I ended up after pulling fuel trying to get my ++40's to work. The timing curves seem less aggressive than the 2.5 ones and I wanted to see if the switchable boost worked for me with that cal - best I can tell there isn't any difference. Still working that quirk. As I mentioned, I depinned the entire 60 way to ohm out the wires and clean the contacts. No change after that procedure. It's set-up on the cruise control which pass all of its switch tests so .........? I'd be bored if I didn't have to putter with something :D .