TCS/HVAC-NO COMM

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TCS/HVAC-NO COMM

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Corvette Forum >> Corvette Models >> Corvette C5 Forum >> TCS/HVAC-NO COMM

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TCS/HVAC-NO COMM - 12/20/2007 8:22:38 AM

Mitch01vette

Posts: 9
Joined: 11/22/2007
Status: offline

I 'm getting NO COMM on the TCS when I run the DIC codes. I'm also getting NO COMM on HVAC at times. The HVAC issue just came up last night. The climate control wouldn't come after getting in the car from a shopping trip. I was driving back home and it just came all of the sudden. The TCS light used to come on only every now again but now it's on all the time. Before, I could check my codes and would get TCS-C1277 H - Requested torge signal ckt malfunction. I also got these codes:BCM B0432 H Rear defogger relay circuitSDM U1040 H Loss of communication w/TCSRDCM B 2265 H Horizontal position sensor faultPCM P1571 H ASR desired torquePCM P1689 H TCS delivered torqe circuitIPC U1040 H Loss of communication w/tcs I checked the grounds around the engine compart that I could see with VOM and measured resistance and it's around .1 ohms. I think the points I checked are G101,G102,G104,G108G106,G202.

Post #: 1

RE: TCS/HVAC-NO COMM - 12/20/2007 11:06:10 AM

extanker

Posts: 236
Joined: 1/7/2007
Status: offline

i would disconnect the batt. for a few mins. to clear all the codes then drive it and if CEL comes on get that code # .you got alot of history codes in there so dont go chasing them .

(in reply to Mitch01vette)

Post #: 2

RE: TCS/HVAC-NO COMM - 12/20/2007 12:48:20 PM

Mitch01vette

Posts: 9
Joined: 11/22/2007
Status: offline

I tried disconnecting the battery for 30 minutes and no help. I get the service engine soon and and I re-checked the codes and still have no comm. I did notice the volts read 11.4 on the display and I checked with vom on the batt. and it reads 11.9. I don't know if that's enough to effect anything.

(in reply to extanker)

Post #: 3

RE: TCS/HVAC-NO COMM - 12/21/2007 4:21:01 AM

extanker

Posts: 236
Joined: 1/7/2007
Status: offline

that voltage is WAY to low if its running.you got a CEL right away? what codes came up ? h or history codes shouldnt come up yet as youve no history.what problems are you having with the car?i dont use the DIC for codes [i have a snap on scan tool it tells ya c for current or h for history] you fix current first in the order they are shown.if ya got those low volt readings while the car is running i,ld look at that first [low volts drives the system crazy]

(in reply to Mitch01vette)

Post #: 4

RE: TCS/HVAC-NO COMM - 12/21/2007 7:13:48 AM

Mitch01vette

Posts: 9
Joined: 11/22/2007
Status: offline

I use the DIC for looking at the codes. The voltage runs about 13.7 with the car. I noticed when I first start the car that the voltage takes 5-10 sec. for the display to change. I also noticed that the alternator is VERY hot after only running a few min. The alternator also has a bad bearing because yo can hear it at idle. I'm sure that something to do with it getting hot.

(in reply to extanker)

Post #: 5

RE: TCS/HVAC-NO COMM - 12/21/2007 9:43:32 AM

extanker

Posts: 236
Joined: 1/7/2007
Status: offline

your running voltage is ok.these are high amp alts so start up noise is ok as is heat .although an old and weak batt will make the alt. work hard thus noisey. okay back to codes .what did ya get in C codes not H .IVE HAD MANY mine too [c5,s] that run great with no troubles and they have a doz. codes stored in them all history.you can pop a code just by disconnecting the batt. but it doesnt trigger a CEL .so give me C codes

(in reply to Mitch01vette)

Post #: 6

RE: TCS/HVAC-NO COMM - 12/24/2007 5:55:19 AM

mech259

Posts: 1758
Joined: 1/22/2006
From: Lumberton, Texas
Status: offline

Most of the trouble codes you are reporting are other modules not communicating with the TCS. They are all on a serial buss that reports through the BCM. I would look towrds the TCS as you mentioned you checked grounds. Have you also checked power circuits to TCS. Snap On scanners work ok, but at my shop I have a Tech 2 scanner that we use on GM's where you can gain more informational access. Can't remember if the Snap On does a Class 2 data check to see if all the modules are reporting, but that will be what you have to have done next. All the U codes are buss communication codes. P codes are PCM, B codes are body control codes. Be careful measuring resistance as that will fool you. You need to measure voltage drop at ground points by touching one lead to battery ground and the other lead to the ground point while in DC volts mode. Should be no more the .10 volts for a good connection.

< Message edited by mech259 -- 12/25/2007 9:16:13 AM >

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(in reply to Mitch01vette)

Post #: 7

RE: TCS/HVAC-NO COMM - 12/24/2007 12:55:47 PM

Mitch01vette

Posts: 9
Joined: 11/22/2007
Status: offline

I checked voltage from battery to grounds aroud the engine and checked good. I disconnected the battery again and cleared codes. The same codes keep coming up. The climate doesn't come on when turning the ignition but does come on after the engine is turned on and running for few seconds. As I mentioned on the previous post, the voltage doesn't up to 14v until after running a few seconds. I removed the tension off the alternator belt and turned the alternator by hand. You can a hear a hi pitched squeal like a bad bearing. It seems like a voltage or a ground problem to me but I'm not an expert. Would a scanner from Advance auto or somewhere be helpful at reading more specific codes?

(in reply to mech259)

Post #: 8

RE: TCS/HVAC-NO COMM - 12/25/2007 4:51:55 AM

extanker

Posts: 236
Joined: 1/7/2007
Status: offline

no those cheap scan tools [code readers] cant hold a candle to a tech2 or snap on.the higher end tools allow you to command tests

(in reply to Mitch01vette)

Post #: 9

RE: TCS/HVAC-NO COMM - 12/25/2007 7:29:22 AM

Mitch01vette

Posts: 9
Joined: 11/22/2007
Status: offline

Does anyone know the power suppy terminals to check on the TCS/ABS module? I checked fuses and all seem to be OK.