Where is Check Engine Light?

[Racinfan83]

Read somewhere that the CEL is supposed to come on when you turn the key to "on". Was working on the car yesterday and couldn't find it. Where is it? Panel above the radio or the main instrument panel? How hard is it to change the bulb and can I read the codes if I have one with an OBD II scanner?

[Dynomite]

Read somewhere that the CEL is supposed to come on when you turn the key to "on". Was working on the car yesterday and couldn't find it. Where is it? Panel above the radio or the main instrument panel? How hard is it to change the bulb and can I read the codes if I have one with an OBD II scanner?

Panel above radio.

DIAGNOSING ECM CODES
Marc Haibeck code reading (http://www.zr1specialist.com/HAT%20Web/Tech%20Info/aldl.htm) Updated by Marc April 30, 2014
Clearing Codes (http://www.zr1.net/forum/showthread.php?p=128420)
Codes (http://www.zr1.net/forum/showthread.php?p=108140)
Code 9 Low freon (http://www.zr1.net/forum/showthread.php?p=92190)
Code 12 normal (http://www.zr1.net/forum/showthread.php?p=3686)
Code 12 is begining of diagnostic code reading (http://www.zr1.net/forum/showthread.php?p=144625)
Code 16 DIS system fault (http://www.zr1.net/forum/showthread.php?p=84415)
Code 21 Throttle position (http://www.zr1.net/forum/showthread.php?p=89290)
Code 23 Vehicle speed (http://www.zr1.net/forum/showthread.php?p=62962)
Code 24 Speed sensor (http://www.zr1.net/forum/showthread.php?t=8721)
Code 31 Cam sensor (http://www.zr1.net/forum/showthread.php?p=51010)
Code 32 EGR (http://www.zr1.net/forum/showthread.php?p=91253)
Code 33 MAP sensor hose (http://www.zr1.net/forum/showthread.php?p=12789)
Code 41 ECM/CCM error (http://www.zr1.net/forum/showthread.php?p=87430)
Code 41 Bad ECM (http://www.zr1.net/forum/showthread.php?p=117460)
Code 42 Electronic Spark Timing (EST) (http://www.zr1.net/forum/showthread.php?p=95902)
Code 43 knock sensor (http://www.zr1.net/forum/showthread.php?p=65245)
Code 55 Lean 02 (http://www.zr1.net/forum/showthread.php?p=58321)
Code 56 Vacuum pump (http://www.zr1.net/forum/showthread.php?t=4079)
Code 61 Vacuum/MAP sensors (http://www.zr1.net/forum/showthread.php?p=89435)
Code 61 secondary vac solenoid (http://www.zr1.net/forum/showthread.php?p=68706)
Code 63 Oxygen sensor (http://www.zr1.net/forum/showthread.php?p=89402)

[WVZR-1]

Read somewhere that the CEL is supposed to come on when you turn the key to "on". Was working on the car yesterday and couldn't find it. Where is it? Panel above the radio or the main instrument panel? How hard is it to change the bulb and can I read the codes if I have one with an OBD II scanner?

It is generally assumed that an OBDII scanner won't do OBDI but the higher ended ones will with the correct adapters etc.

This DIY will let you do everything that you need from the DIC and the read-out in the cluster. ECM/CCM - both.

http://tech.corvettecentral.com/2011/01/c4-diagnostic-trouble-codes/

Before tearing into the DIC do the correct diagnostics from the FSM for "NO SES" - 6E3-A-14 thru 16

I believe Cliff is missing a couple codes and his description/definition isn't "FSM EXACT" either. I'd rely on the FSM here. Second read is I guess he didn't intend to do a "list of". I couldn't get his Haibeck link to work either:

http://www.zr1specialist.com/HAT%20Web/Tech%20Info/aldl.htm

[Dynomite]

It is generally assumed that an OBDII scanner won't do OBDI but the higher ended ones will with the correct adapters etc.

This DIY will let you do everything that you need from the DIC and the read-out in the cluster. ECM/CCM - both.

http://tech.corvettecentral.com/2011/01/c4-diagnostic-trouble-codes/

Before tearing into the DIC do the correct diagnostics from the FSM for "NO SES" - 6E3-A-14 thru 16

I believe Cliff is missing a couple codes and his description/definition isn't "FSM EXACT" either. I'd rely on the FSM here.

Yeb....you are correct for sure....those happen to be the codes I found discussed by members in posts which describes more detail related to experiences with the code itself (I am always updating that list as I find posts addressing specific codes) :thumbsup:

And your Diagnostic Trouble Codes TIPS (http://tech.corvettecentral.com/2011/01/c4-diagnostic-trouble-codes/) by Corvette Central is a great link :cheers:

And thanks for that updated Marc Haibeck Link which Marc just updated Apr 30 2014 Marc Haibeck code reading (http://www.zr1specialist.com/HAT%20Web/Tech%20Info/aldl.htm)

[Racinfan83]

Ok cool. I have an FSM
Have you noticed “SYS” intermittently showing up in your 1990-1996 Corvette’s speedometer display? This means there is a trouble code stored in one of the on-board control modules. - See more at: http://tech.corvettecentral.com/2011/01/c4-diagnostic-trouble-codes/#sthash.JlckmH9o.dpuf
Ok now I'm confused. And I'm at work so don't have FSM. This says it is an "SYS" and it shows up on speedometers panel. From what you guys said it is an "SES" light on the info panel. So is there 2 different "check engine lights"?

[Kevin]

There is an ses light that blinks where your millage is. And another orange one in the drivers information center (d.i.c). The one in the dic is orange. I'm not sure what the sys light is triggered by. How I long for a car with no computers some times

[Racinfan83]

Yeah I hear that ... I gotta look again now. I know I don't have the SYS thing coming on, and I may have missed the SES on the info center. Does it actually say Service Engine Soon, or just SES? I was looking for the little "engine" picture like all my other vehicles has...

[We Gone]

Got this off CF. referring to SYS

Here's all the info you'll need to clear it

How to View Stored Diagnostic Codes on 1994 – 1996 Corvettes

You display codes on the digital LCD speedometer readout, by using a re-shaped paper clip to short ALDL pin 4 to pin 12.

1994 – 1996 Corvette ALDL connector:



You short pin "12" to pin "4" and turn the ignition switch to "On" without starting the engine.

The speedometer will display any codes using the same protocol as the 1990-1993 model but there are some changes in the designation for the modules plus additional modules are added:

Module "1" is still the CCM module.

Module "4" is now called the PCM module (Powertrain Control Module) because automatic transmission computer control was added to Engine Control Module in 1994.

Module 7 (on the 1996 model only) is the RTD module. (This is the Real Time Dampening module which replaced the Selective Ride Control module in 1996).

Module 9 is the ABS/ASR module number from 1994 through 1996.
Finally, Module "A", the DERM (Dynamic Energy Control Module --- (the air bag control module) will be requested to show any codes.

Just like the 1990-1993 display, you read the codes on the speedometer (big) and read the module number on the trip odometer (small).

A series of dashed lines for instance “ - - -“ indicates no more stored codes for that module.

A code showing as “C12” for the CCM module (module #1) means no codes are stored. So C12 is a good thing to see.

Again, you can cause the codes to repeat by turning the ignition off for five seconds and then back on.

Turn the ignition off and remove the short to restore normal operation.

To clear codes in the CCM proceed as follows:

1. With ignition "off" ground terminal #12 of the DLC (use bent paper clip to connect pin 4 to pin 12)

2. Turn ignition "on".

3. Press trip/odo button on the DIC until 1.7 appears in the trip
monitor area of the instrument cluster.

4. Press eng/met button on the DIC & hold until "---" appears in the
speedometer area of the cluster, this will clear CCM DTC'S.


To clear PCM/ECM codes do the following:


1. Press the trip reset button on the DIC until the desired system is displayed. In this case it will be 4.0.

2. Press trip/odo button on the DIC until the desired diagnostic mode(4.7) is displayed on the trip monitor area of the cluster.

3. Press & hold the eng/met button on the DIC until "---" is
displayed in the speedometer area of the cluster, this will clear PCM codes.


To clear ABS/ASR codes do the following:

Same as above but you’re looking for “9.7” on the trip odo

[Kevin]

Sorry it's sys in the speedo i had

[Hib Halverson]

Read somewhere that the CEL is supposed to come on when you turn the key to "on". Was working on the car yesterday and couldn't find it. Where is it? Panel above the radio or the main instrument panel? How hard is it to change the bulb and can I read the codes if I have one with an OBD II scanner?

When you turn the key on with the engine off, the MIL should come on during bulb check and, if you don't start the engine it should stay on.

MIL is malfunction indicator light, the modern name for the "Service Engine Soon" or "Check Engine" light.

"Flash Code" diagnostics are available if the MIL works. If it doesn't, I'd repair that, first. The ZR-1 is the only C4 which supports flash code for MY94/95.

You also can use CCM diagnostics to read fault codes from the car's controllers that store them. The instructions for that are posted above.

For a more detailed description of a ZR-1's OBD, see this web page (http://www.corvetteactioncenter.com/tech/engine_controls/)

[Racinfan83]

OK guys - all good info - and I appreciate it. But first things first - there is no SES light coming on at all. I need to know where exactly in the display panel it is - how to get to it to replace the bulb, and what bulb it takes. Unless there is another reason it doesn't work????:confused:

[-=Jeff=-]

Start with checking the bulb first.

Have you removed the radio in the car yet? Getting to the info center of the same. Remove console bezel. Then center a/c vent then the radio bezel. The info center has 2 or 3 books holding it in.. Then you can get to the bulb.

I think the MIL is the second from the left on the bottom row

[WVZR-1]

Bottom row, SES (Service Engine Soon) is third from left with the first position being "empty", the second "battery, and next SES (amber). See FSM 8C-4. Replacement is in maybe the next 2 - 3 pages.

It's a PC bulb socket and for diagnostics I would think you could just borrow one from anywhere except the battery location. There is likely a "unused one" in the DIC so you could compare the bulb sockets present to the chart on 8C4 and use one that serves no function. It seems to me the second row fourth from left has no function but there's likely a bulb socket there.

[-=Jeff=-]

Bottom row, SES (Service Engine Soon) is third from left with the first position being "empty", the second "battery, and next SES (amber). See FSM 8C-4. Replacement is in maybe the next 2 - 3 pages.

Well I had the right row.. Lol only off by one

[WVZR-1]

If you didn't want to do the DIC removal you could do the diagnostics first for "no light". Those are in the FSM at 6E2-A-16 & 17.

Well I had the right row.. Lol only off by one


It is the second "functional"

[-=Jeff=-]

Yeah I guess going that way..

WV,

I am amazed on your ZR-1 knowledge

[Racinfan83]

Ok Thanks! Now I know where to start. Haven't had radio out but doesn't sound too bad...

[Racinfan83]

UPDATE: Well I found it. Got out my FSM and did the diagnostic for "no SES light" Pulled ECM and ran test light to B1. SES light was supposed to come on if bulb was good/nothing else wrong. It didn't. So I figured it was the bulb - and was just not in the mood to take things apart today. Unhooked the battery for a while to see if it would reset the A/C (not sure if it did or not - have to drive it later). Anyway - when I got back in the car and turned key on - there was the "SES" light. :o
SO - it was not working before, now it appears that it is. So either I pissed it off by trying to diagnose it, or the battery unhook did something to fix it?? No idea but at least it comes on now and goes off when car starts running....:confused:

[Schrade]

UPDATE: Well I found it. Got out my FSM and did the diagnostic for "no SES light" Pulled ECM and ran test light to B1. SES light was supposed to come on if bulb was good/nothing else wrong. It didn't. So I figured it was the bulb - and was just not in the mood to take things apart today. Unhooked the battery for a while to see if it would reset the A/C (not sure if it did or not - have to drive it later). Anyway - when I got back in the car and turned key on - there was the "SES" light. :o
SO - it was not working before, now it appears that it is. So either I pissed it off by trying to diagnose it, or the battery unhook did something to fix it?? No idea but at least it comes on now and goes off when car starts running....:confused:

Cool, but NOT so cool there RF (problems that SEEM to go away by themselves).

Might still be a good idea to pick an easy access point in the circuit, and start ... *GULP* ... following the circuit, one way or the other, from terminal to terminal. NEVER fun, but necessary, ESPECIALLY if other toys are on the same line, OR, if the ground is NOT dedicated, but is shared by other stuff.

[Racinfan83]

Yeah I'm not good with electrical diagnosis at all. Couldn't read a meter if I tried. Test light is about the extent of my knowhow. I can fix a lot of stuff - but electric has never been my thing. According to the FSM the SES light is on a dedicated pin - which appeared to be correct. It is possible that when I stuck the tester in the connecter I scraped off some corrosion, or the connecter was just not in exactly right?
Now you may have something with the grounds - I should probably try to find the ground wire attachments and remove/clean them...