Major work necessary - rebuild or replace? [Forums - C4 Technical]

C4 Technical > Major work necessary - rebuild or replace?
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Schrade	Major work necessary - rebuild or replace?	#1
Elite Guru eastern NC / e-i-e-i-o 1909 Posts Member since: 2008/8/15 2:01	I've been tracing some electrical problems (with a fine-tooth comb, literally) for 2 months now, about, but now the plan needs to go macro. I have not replace parts blindly, and I know that approach will NOT solve this problem. From another forum: Took a little ride, and all 3 codes lit up for me - H41 ICC open, H64 O2 lean, H72 VSS loss - ALL INTERMITTENT. And a little smoke, occasionally. So it's time to drop the wrenches, and change the attack plan to the macro scale. The harness is bad. Part motor harness, and probably part interior harness. It has to be pulled all the way and inspected / replaced. Oil is getting out somewhere to the Pside exhaust manifold (V/C gasket NOT). I have not checked the compression, because before the electrical problems began 2 months ago, it ran perfect. Still does, when electrical faults are 'off'; again, except for the occasional smoke. So, I can pull the entire top end (and get some modding and tuning to the heads), which will still make it difficult to pull the harness and re-install it, or replace. If I had a shop, I would do it myself. Take the car in and get the motor pulled, and rebuilt, or get a new motor. Suggestions? Ideas?
	Posted on: 2008/8/23 23:21

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bogus	Re: Major work necessary - rebuild or replace?	#2
Grand Imperial Pooh-Bah San Pedro, CA 20859 Posts Member since: 2005/9/7 0:00	What is the vintage/options/mileage? I need some specs on the car before assessing what is the best move. It sounds like a 90+, judging from the codes you are reading off.
	Posted on: 2008/8/24 2:37
	_________________ The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me
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NEVRL8T	Re: Major work necessary - rebuild or replace?	#3
Guru Little Rock, AR 74 Posts Member since: 2007/2/21 0:00	Quote: bogus wrote: What is the vintage/options/mileage? I need some specs on the car before assessing what is the best move. It sounds like a 90+, judging from the codes you are reading off. Its a 1994. Thats all I know.
	Posted on: 2008/8/24 2:45

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Schrade	Re: Major work necessary - rebuild or replace?	#4
Elite Guru eastern NC / e-i-e-i-o 1909 Posts Member since: 2008/8/15 2:01	Hey Lee... '94 auto, 87k. Lots of evidence of a mouse when I got it 18 months ago. Drivetrain is tight, burn was very clean when problems started 2 months ago. There's a few pics of the oil residue on the side of the block here: http://www.digitalcorvettes.com/forums/showthread.php?t=106692 and a couple of dozen pics of EXTENSIVE diagnostic work at CF; thread entitled 'MERGED ... ', page 1 or 2, username Zeitgeist57 a little over 3,000 hits as of earlier this week... If you see *anything*, chime in!
	Posted on: 2008/8/24 2:52

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bogus	Re: Major work necessary - rebuild or replace?	#5
Grand Imperial Pooh-Bah San Pedro, CA 20859 Posts Member since: 2005/9/7 0:00	Ok... a few thoughts: 1. Mouse damage is a BITCH. These are good harnesses and don't wear on their own, it takes either a mouse or a hack job. You will have to tear into the dash for this one. 2. Oil leaks... looks normal, really. The car has some miles, it's also old. They weap. Some will ooze from the pan, others will come from oil changes, others, everytime you open the dipstick. Also, road grime will show. These are not the most leak free engines made. Check the back of the intake, too. That's a great source of leaks. Degrease the engine - simple green it - and see if there is any sign of fresh oil. 3. I kinda go back to one... the O2 wiring is close to the exhaust and could be fouled. 4. Get an O2 socket kit. They are about $20.00 or so. They have a deep socket with a gash to pass by the wires and an offset crows foot. Use it inverted... be creative with the crowsfoot and you will get the O2s. Get the Autozone one... it's OEM brand or something. Who needs snap on for a tool you will use once a year, tops!?! 5. You will need a good digital volt meter (I like Fluke) and a test light to debug the system. I know you borrowed an FSM, but you will really need one to debug these issues.
	Posted on: 2008/8/24 3:45
	_________________ The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me
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Schrade	Re: Major work necessary - rebuild or replace?	#6
Elite Guru eastern NC / e-i-e-i-o 1909 Posts Member since: 2008/8/15 2:01	Hey Andy... I haven't pulled the dash, or employed the 'new parts assault'. I've done EVERYTHING else. E-V-E-R-Y-T-H-I-N-G. Let me put that another way EVERY THING. See the 2 threads, and probably 80 - 90 pics in those 2 threads mentioned above. I didn't snap pics of the O2-cleaning with a toothbrush, that I did this morning, before swapping front and rear Pside O2's. EVERYTHING IS NOW SPOTLESS TOO. Of course, cleaning was included in EVERYTHING. Spotless as in, 'turn-a-bolt-back -into-it's-hole-with-one-finger-cause-the-bolt-hole-is-so-clean' spotless. And there's about 60 more pics in my intake-cleaning gig from May. More of the same spic n span cleaning, like cleaning injector ports with a Q-tip, pulling injector screens, etc., ...
	Posted on: 2008/8/24 4:27

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bogus	Re: Major work necessary - rebuild or replace?	#7
Grand Imperial Pooh-Bah San Pedro, CA 20859 Posts Member since: 2005/9/7 0:00	hm... lemme try this again... I suggest pulling the dash only as a way to see of the mouse had lunch on your harness. The goal is to get to the CCM and test the connections between the CCM and ECM. You also need to test the connection between the ECM and the various sensors. All the cleaning of the O2s in the world won't fix a bad wire or a bad O2. Those pics of the oil leaks - are those before or after cleaning? It looks before.
	Posted on: 2008/8/24 19:54
	_________________ The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me
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Schrade	Re: Major work necessary - rebuild or replace?	#8
Elite Guru eastern NC / e-i-e-i-o 1909 Posts Member since: 2008/8/15 2:01	Quote: bogus wrote: hm... lemme try this again... I suggest pulling the dash only as a way to see of the mouse had lunch on your harness. The goal is to get to the CCM and test the connections between the CCM and ECM. You also need to test the connection between the ECM and the various sensors. All the cleaning of the O2s in the world won't fix a bad wire or a bad O2. Those pics of the oil leaks - are those before or after cleaning? It looks before. The oil leak pics are taken before I cleaned. What does this look like to you? I rubbed under the lip of the V/C at #8 while the motor was runnin', hot, with a heavy glove, and got NO oil. The gaskets are new and are well-seated I'm sure. Can the head give oil somehow, and still run perfect??? (when the electrical faults are 'off', that is) OR, how could it be comin' from the intake rear, and gettin' to in front of #8 exhaust port??? I am completely stumped...
	Posted on: 2008/8/25 0:34

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bogus	Re: Major work necessary - rebuild or replace?	#9
Grand Imperial Pooh-Bah San Pedro, CA 20859 Posts Member since: 2005/9/7 0:00	air flow is a tricky thing. The intake is my #1 source for an oil leak. I would be shocked if the heads were the cause. Oil falls down and has no pressure at the head gaskets.
	Posted on: 2008/8/25 0:54
	_________________ The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me
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Schrade	Re: Major work necessary - rebuild or replace?	#10
Elite Guru eastern NC / e-i-e-i-o 1909 Posts Member since: 2008/8/15 2:01	Quote: bogus wrote: hm... lemme try this again... I suggest pulling the dash only as a way to see of the mouse had lunch on your harness. The goal is to get to the CCM and test the connections between the CCM and ECM. You also need to test the connection between the ECM and the various sensors. Well, pull the dash? Even if I put a new twister under the hood, someone might have got a grub-on my wiring, and I know they were there before I bought it. Holy cow!!! Mouse grubbin' on PC wirin'!!! http://ic030059.ithaca.edu/~briotta/observatory/Mouse2.html OMIGOSH!!! Quote: By the way, there is no code for "Mouse nest in MAF" (maybe they're saving it for OBD3). NOICE WORK!!!
	Posted on: 2008/8/25 19:29

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Schrade	Re: Major work necessary - rebuild or replace?	#11
Elite Guru eastern NC / e-i-e-i-o 1909 Posts Member since: 2008/8/15 2:01	Definite gnaw damage pic 7... Anybody wanna' see the rest of the dash pull pics? I snap 'em anyway, for reference, and post 'em in case anybody gets somethin' out of 'em...
	Posted on: 2008/8/25 21:59

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Schrade	Re: Major work necessary - rebuild or replace?	#12
Elite Guru eastern NC / e-i-e-i-o 1909 Posts Member since: 2008/8/15 2:01	Screws HAVE TO go back in the hole as soon as a piece is out of the way... Problem is, some pieces are so big you have 7 screws holding in your teeth so you don't lose track of them, and 3 screws from the piece that you almost had out except you have to remove another piece first while you hold those 3 in your eyebrow, then a telemarketer calls ya'... Attach file: hpim0736.jpg (205.62 KB) hpim0737.jpg (155.88 KB) hpim0738.jpg (122.14 KB) hpim0739.jpg (212.63 KB)
	Posted on: 2008/8/27 20:12

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Schrade	Re: Major work necessary - rebuild or replace?	#13
Elite Guru eastern NC / e-i-e-i-o 1909 Posts Member since: 2008/8/15 2:01	When I brought it home in '07, I found a Taco sauce chewed open, under the seat. Somethin' tells me he didn't flush, opting for the absorbent foam Depends instead... No way we're attackin' the squalor from below - some of that mouse jam could fall into my pretty mug. Attach file: hpim0740.jpg (194.60 KB) hpim0741.jpg (247.18 KB) hpim0742.jpg (166.16 KB)
	Posted on: 2008/8/27 20:51

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bogus	Re: Major work necessary - rebuild or replace?	#14
Grand Imperial Pooh-Bah San Pedro, CA 20859 Posts Member since: 2005/9/7 0:00	Musta been a mouse with taste...
	Posted on: 2008/8/27 21:08
	_________________ The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me
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Randyj75	Re: Major work necessary - rebuild or replace?	#15
Guru Newb MD 129 Posts Member since: 2006/2/10 0:00	Sounds like a Mexican mouse. BTW, I feel your pain. The first year I had my car, I found a rat (not a mouse) was living in our garage, and was sleeping on my intake, or at least using it as aplace to potty. I was lucky to get him before he did any damage. Good Luck, Randy
	Posted on: 2008/8/28 7:10
	_________________ '90 Corvette, M6,a few mods, more to come
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Schrade	Re: Major work necessary - rebuild or replace?	#16
Elite Guru eastern NC / e-i-e-i-o 1909 Posts Member since: 2008/8/15 2:01	Quote: Randyj75 wrote: Sounds like a Mexican mouse. Uhyup! Andele ANDELE!!!!!!!
	Posted on: 2008/8/28 7:21

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Schrade	Re: Major work necessary - rebuild or replace?	#17
Elite Guru eastern NC / e-i-e-i-o 1909 Posts Member since: 2008/8/15 2:01	This is how far I've gotten on dash disassembly. NOTICE THERE ARE NO EMPTY SCREW HOLES. PUT EVERY SINGLE SCREW BACK IN THE HOLE WHEN EACH PIECE IS REMOVED. I put my computer vacuum attachments on the shop-vac and went through all the orifices, then I put in the controls this morning so I could go to see the mechanic that the Chevy dealership referred me to... He suggested replacing the O2 even tho' it is an intermittent, and demonstrates intermittence while logging on Tech I, and Genisys scanner.And, even tho' it started out at the same time my other 2 electrical problems started (2 months ago) as an 'OPEN O2 circuit', not 'LEAN O2', as it is now. Of course, the H41 ICC fault, and the H72 VSS loss were nowhere to be found when I was there................. Attach file: hpim0743.jpg (246.08 KB) hpim0744.jpg (185.28 KB) hpim0745.jpg (218.30 KB) hpim0746.jpg (223.12 KB) hpim0747.jpg (247.68 KB)
	Posted on: 2008/8/30 4:50

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bogus	Re: Major work necessary - rebuild or replace?	#18
Grand Imperial Pooh-Bah San Pedro, CA 20859 Posts Member since: 2005/9/7 0:00	looks very familier... my 92 is in about the same shape. Now... thinking time... the H41 is directly related to the data line between the PCM and the CCM. Test that. That harness, IIRC, goes up into the engine via the firewall, near the EGR. I would check that are for heat related damage.
	Posted on: 2008/8/30 5:40
	_________________ The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me
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Schrade	Re: Major work necessary - rebuild or replace?	#19
Elite Guru eastern NC / e-i-e-i-o 1909 Posts Member since: 2008/8/15 2:01	Quote: bogus wrote: Now... thinking time... the H41 is directly related to the data line between the PCM and the CCM. Test that. Um ... uh-oh... promise CCM-PCM comm's link on the H41? And NOT Ignition Control Circuit [failure] 'open'? Have I been doin' it wrong since the beginnin'? '94, ALDL module '4' H41??? Tell me I have, so I can say all really IS well with the ICC circuit??????????????? And maybe the H72 VSS loss is because some tranny selector wiring goes through the same harness in the firewall???
	Posted on: 2008/8/30 8:56

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BrianCunningham	Re: Major work necessary - rebuild or replace?	#20
Senior Guru Boston, MA for the most part :) 7763 Posts Member since: 2007/12/30 0:00	damn! I guess I got lucky when I stored mine
	Posted on: 2008/8/30 16:06
	_________________ Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com
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bogus	Re: Major work necessary - rebuild or replace?	#21
Grand Imperial Pooh-Bah San Pedro, CA 20859 Posts Member since: 2005/9/7 0:00	whew... my research is confusing me. I thought H41 was the same for both CCM and ECM (and that meant CCM com failure. I was wrong... Now... according to my book, Corvette Fuel Injection and Electronic Ignition: 1982-2001, by Charles Probst, indicates that for a 1994, the H41 means cylinder select. Does that means that something is out of wack with the sequential injection?
	Posted on: 2008/8/30 17:52
	_________________ The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me
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Schrade	Re: Major work necessary - rebuild or replace?	#22
Elite Guru eastern NC / e-i-e-i-o 1909 Posts Member since: 2008/8/15 2:01	Quote: bogus wrote: whew... my research is confusing me. I thought H41 was the same for both CCM and ECM (and that meant CCM com failure. I was wrong... Now... according to my book, Corvette Fuel Injection and Electronic Ignition: 1982-2001, by Charles Probst, indicates that for a 1994, the H41 means cylinder select. Does that means that something is out of wack with the sequential injection? I'm confused without doin' research. And I'm gettin' more confused even... What is the difference between module #1, #4, #9, and module A, in the ALDL display??? Where is this in the FSM? I don't believe it is in FSM volume 2, which I have right now. Is it anywhere here? Anywhere on the web? I found this: Quote: Sequenced Code Recovery - 1994 through 1996: In 1994, Chevrolet went to a 16 pin ALDL connector in preparation for the federally mandated change to the much more capable OBD-II (On Board Diagnostics - Version 2) system. As with the 1990-1993 model, you can display codes on the speedometer but the pins to be shorted are different: Beginning in 1994, you short pin "12" to pin "4" and once again 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. So now that I have a H72 in module #1, AND in module #9, how do I diagnose that with the FSM volume 2?
	Posted on: 2008/8/30 22:56

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bogus	Re: Major work necessary - rebuild or replace?	#23
Grand Imperial Pooh-Bah San Pedro, CA 20859 Posts Member since: 2005/9/7 0:00	Here you go: Module #1 is the CCM - Central Control Module. Module #4 is the PCM - Powertrain Control Module. Module #9 is the EBCM - Electronic Brake Control Module (ABS/ASR). Module A? Never heard of that. By selecting to display the error codes on the speedometer, you are getting them from the CCM; it is reading the codes and handing them back. If you get the codes from the flashing SES, then that's direct from the PCM. In my 1992 FSM, the CCM code procedures are found in section 8D, book 1, titled Central Control Module. I hope this clears up some stuff for ya...
	Posted on: 2008/8/30 23:20
	_________________ The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me
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Schrade	Re: Major work necessary - rebuild or replace?	#24
Elite Guru eastern NC / e-i-e-i-o 1909 Posts Member since: 2008/8/15 2:01	Quote: bogus wrote: Here you go: Module #1 is the CCM - Central Control Module. Module #4 is the PCM - Powertrain Control Module. Module #9 is the EBCM - Electronic Brake Control Module (ABS/ASR). Module A? Never heard of that. By selecting to display the error codes on the speedometer, you are getting them from the CCM; it is reading the codes and handing them back. If you get the codes from the flashing SES, then that's direct from the PCM. In my 1992 FSM, the CCM code procedures are found in section 8D, book 1, titled Central Control Module. I hope this clears up some stuff for ya... Yes sir, it does - I just found the same reference to section 8D CCM in the 'diagnostic aids', in my volume 2. All problems are solved - just makin' a new checklist... matches looooong stick marshmallows
	Posted on: 2008/8/30 23:39

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Matatk	Re: Major work necessary - rebuild or replace?	#25
Webmaster SW Chicago Burbs 22805 Posts Member since: 2008/1/7 0:00	Quote: All problems are solved - just makin' a new checklist... matches looooong stick marshmallows We should make smores! At least you have a sense of humor about it. Hope you get it all worked out. I wish I could help more, but I know zero about diagnostics on the LT1...I need to see it in front of me. Matthew
	Posted on: 2008/8/31 0:16
	_________________ 2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP
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Schrade	Re: Major work necessary - rebuild or replace?	#26
Elite Guru eastern NC / e-i-e-i-o 1909 Posts Member since: 2008/8/15 2:01	Quote: bogus wrote: That harness, IIRC, goes up into the engine via the firewall, near the EGR. I would check that are for heat related damage. I tried to pull this harness that you refer to, FROM the firewall OUTside, I couldn't figure how to disconnect it. FSM isn't much help on connectors. Does it disconnect from the engine compartment? Or from INSIDE???
	Posted on: 2008/8/31 18:04

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bogus	Re: Major work necessary - rebuild or replace?	#27
Grand Imperial Pooh-Bah San Pedro, CA 20859 Posts Member since: 2005/9/7 0:00	it is bolted in, tho, so that might be how it disconnects. The bolt is on the outside... and I am afraid it's on the bottom... which will make it damned near impossible to reach. Would I would do is pull open the convolute near the firewall and see what the wiring condition is like.
	Posted on: 2008/8/31 18:38
	_________________ The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me
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cuisinartvette	Re: Major work necessary - rebuild or replace?	#28
Elite Guru 1782 Posts Member since: 2005/9/16 0:00	Wiring harnesses...you are guys are nuts, brave or electrically inclined to dig into them the way you do. No thanks!
	Posted on: 2008/8/31 19:47
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Schrade	Re: Major work necessary - rebuild or replace?	#29
Elite Guru eastern NC / e-i-e-i-o 1909 Posts Member since: 2008/8/15 2:01	Quote: cuisinartvette wrote: Wiring harnesses...you are guys are nuts, brave or electrically inclined to dig into them the way you do. No thanks! What's up there Ron... Nuts huh? Did it take you all that time to figure this out? Or did you have help? And to think I'm allergic to electricity too! Gives me the shakes. Makes me look around for buddies to share with too - ya' know - get me grounded like...
	Posted on: 2008/8/31 23:27

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Schrade	Re: Major work necessary - rebuild or replace?	#30
Elite Guru eastern NC / e-i-e-i-o 1909 Posts Member since: 2008/8/15 2:01	I got my hands on FSM V1 today. The light is gettin' bright!!! from DC Quote: What's up Clay... I got FSM V1 from another dealer today. Drove the vette to the next town, 53mph, on cruise, and it was at 31.9 mpg's when I got back. Ran like a top. Fixed O2, and no more runnin' in open loop. I have no engine problems. I found my H41 in FSM CCM diagnostics, faulty comms from CCM to PCM. There is no ignition fault in mine, it is CCM. Someone might have told me that in the last 2 1/2 months, and I missed it, or hard head ignored it. And H72 is NOT VSS, it is LCD output. I do have some testing yet to do, and might have serious diggin' to do in the dash, beyond where I am now, but the light at the end of this tunnel is gettin' really bright. Your 41, being in module 4, is PCM. It IS an ignition fault. With a multimeter, you should be able to do the test as posted in the schematic somewhere in one of the forums, in a few minutes. You're gonna' have to do it hot - when you get home from afternoon commute, to catch the fault.
	Posted on: 2008/9/4 19:52

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