I can scan some info on trouble shooting from my 95 FSM if you'd like? E-mail me at lsylvestri@sbcglobal.net if interested.

 

E-mail sent. Thanks! :thumbsup:

 

Thanks to viscounts kind offer to send me a couple fsm pages, I now know that my IAT sensor appears to be working normally and producing the right resistances/signal, but it still is setting a H25 code and flashing SYS too.

So next I took a fixed 1K resistor (the resistance indicated for an approx 120 degree signal and right in the middle of the correct temp range) and plugged it into the connector in place of the IAT. Reset everything and within a block the car threw another H25 IAT high temp/low voltage code again.

Once again I cleared the codes and then disconnected the IAT completely which should make it throw a low temp code. (H23) It did, but also threw the high temp code (H25) too. Gee, how can it be low and high at the same time??? :WTF

Additional info is that the H25 codes comes up under module 1, the CCM. However the H23 code shows up in module 4, the PCM. I wonder why the codes are showing in two different modules, and also if perhaps the H25 in the CCM is trying to tell me something other than an IAT sensor issue.

So once again any input would be most welcome. The issue is probably something stupid, but at the moment it is being elusive and driving me a bit crazy too. :crazy:

TIA! :thumbsup:

:buhbye:

 

Hey ACECO, did you ever get yours figured out?

 

I haven't fully resolved the issue yet, but I finally received my FSM set and have discovered that what the H25 code in the CCM was trying to tell me was to look in the courtesy light relay circuit as this is what this code in the CCM (vs PCM) means. H25 in the PCM indicates a IAT sensor issue.

So likely I either have a bad relay, dirty contacts or a wiring issue. I have yet to get back and remove the passengers side lower dash cover to get to this relay and check it. However it's on "the list" and I'll get to it soon. I'll also post here the final results when I know what that is. :thumbsup:

:buhbye:

 

According to the info on this page:


http://www.corvette
----------------------------------
buyers.com/c4vettes/codes.htm

module 1 is CCM faults, and your module 1 H25 is courtesy lamp relay circuit open or short. (Module 4 PCM H25 is IAT fault).


Ed.:
format is changing on the link...???:surprised
WTF???????????

I split the link into 2 lines here. Join 'em up without the dot string...
:crazy:

 

Original post was shortly after getting the car and no FSM in hand yet. I wish I had the correct info when I was chasing the wrong code info due to lack of information. :WTF But now that I have my FSM it was easy to see I was looking in the wrong place. :crazy: It's alot easier to know what to do when you have the correct info at hand. :thumbsup:

Thanks for your input. I'll let everyone know the actual solution when I get around to accessing that relay and associated wiring.

:buhbye: