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This is the manual transmission from 1984-1988.

It’s a Borg-Warner Super T-10 with a planetary overdrive attached to the tail shaft housing.
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CorvetteBob Code 33 Saga Continues...
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Ok, so far I've gotten into the car and, following the FsM flow chart, I'm not getting power to the MAF. I AM getting power to the relays. When I check for continuity from relay to the MAF along the purple wire I get NO continuity on a wire that, according to the wiring diagram, runs directly from the relay to the MAF. That means I have a break in the wire somewhere. At this point, I've had to call it a day and come in from the garage due to the cold finally getting to me. I did look at the wiring as it left the MAF. It seems to run down the left (driver) side harness as it passes the injectors and then down the back of the valve cover and into the abyss, presumably to be routed to the MAF power relay. So far, I can see no disruptions in the harness. I'm not looking forward to opening up this Reagan era harness along with the necessary component R&R to try to find this problem. You guys are probably all smarter than me with this, any suggestions that don't involve parting out my car?
As always, thanks in advance for your help.
Posted on: 2015/3/29 21:26
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CorvetteBob Re: Code 33 Saga Continues...
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Again, this is an '86 4+3 coupe.
To add some clarification of my progress
I've been following the FSM trooubleshooting chart for Code 33. So far I've;

With IGN off, disconnected the MAF
run a jump wire from "G" of ALCL Terminal to MAF sensor harness terminal "E". Checked w/ 12v test light. Test light"off".

Disconnected MAF power relay and probed terminals "E" and "C" (ckts 340 & 120) with test light to ground. Light was "ON" on both.

Then probed terminal "B" w/ test light. Light was "OFF".

It now says I should repair open ground circuit. (I don't know where that's hiding).
At this point (just out of curiosity)I used a continuity tester to check my ground. The BLK/WHT wire (ckt 450) I think. touching the continuity tester to the blk/wht wire at the MAF power relay and at the alternator bracket, I got continuity, making me believe the ground is intact. BUT AM I WRONG? I don't know, my strong suit has never been troubleshooting.
Any help is appreciated.

Posted on: 2015/3/30 0:44
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Matatk Re: Code 33 Saga Continues...
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Sorry I saw this late, Bob. I will have to pull out the FSM tomorrow and take a crack at it.
Posted on: 2015/3/30 2:15
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CorvetteBob Re: Code 33 Saga Continues...
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So far my source for the troubleshooting has been the 1986 FSM, page 6E3-A-50 and 6E3-A2-51. The first of these is the initial page for Code 33. The other is the troubleshooting flowchart.
In noticing the circuit #993 to the MAF was dead, and without continuity from relay to sensor, I ran a jump wire from the MAF power relay at "A" over to the harness to plug into the MAF sensor into "E" , thereby bypassing the purple wire circuit #993. With the codes cleared from the ECM, I then started the car. It started and ran fine. The result was the Code 33 was not showing any longer. I think at this point I need to get in and physically trace the purple wire 993 to assure that it does in fact run directly from the MAF back to the power relay without interruption as shown in the diagram on the 1st page listed above. If that is the case, I"ll build a new wire and replace the old wire.
As an afterthought , before I do that, I'm gonna double check the FSM wiring diagram in the main diagram section to make sure the two diagrams concur.
If any of you discover I'm on the wrong path with this, please chime in. I wanna make sure I get this right.
Posted on: 2015/3/31 1:08
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joeld Re: Code 33 Saga Continues...
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I'm not 100% sure a 1989 FSM procedure is the same, but I'm thinking it is.
Based on my book, first step is just simply jumping 12 volts with a fused jumper to terminal G of ALDL, disconnect MAF sensor and then check voltage at harness terminal E (CKT 993) with test light.
This is different from what you did? Or did I read your procedure wrong.

My page for code 33 is 6E3-A-41.

Joel
Posted on: 2015/3/31 3:58
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Schrade Re: Code 33 Saga Continues...
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Excellent job diagnostics. Take time to write up, post, think about it, is when stuff comes to ya'.

We get WAY too used to instant point n click, and don't take time to think it out.

When you tested the Ground Circuit,
"The BLK/WHT wire (ckt 450) I think. touching the continuity tester to the blk/wht wire at the MAF power relay and at the alternator bracket, I got continuity, making me believe the ground is intact." ,
was the ground jumped (to Closed) by your by-pass test wire?

DEFINITELY good diags so far. Can you shoot a snappic of each step? THis sometimes give another 'angle' of thought to diags process...

Does DTC 33 DEFER TO another DTC, if present?

With a relay in the circuit, do you have to 'activate' the relay, with a jumper, to get the MAF circuit to close, for testing?

Posted on: 2015/3/31 13:30
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CorvetteBob Re: Code 33 Saga Continues...
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To answer questions;
Joeld, That's exactly what I did, (as per the troubleshooting flow chart) and got no indication of power. However, I DID have power at the PURPLE wire back at the power relay. If it's a straight shot like the diagram shows, then there's a break in the wire somewhere.
Also, I think different years have some thiings on different pages in the FSM's.


Schrade; for the test I did on the black/wht ground wire, there were no jumpers involved, other than the continuity tester. That ground also showed good at the MAF from the power relay, and I believe from the MAF to the alternator bracket
Posted on: 2015/3/31 21:47
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joeld Re: Code 33 Saga Continues...
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OK, I see what you did on the "jumping" Power to the sensor. Terminal A on the relay is the 340 ckt which is 12v power.

I see two ground wire terminals on the MAF sensor. One is the black/white ckt 551 terminal A, the other is black ckt 476 terminal B.

This is where I'm not sure if your 87 and my 89 has the same wire colors.

Joel
Posted on: 2015/4/1 0:24
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CorvetteBob Re: Code 33 Saga Continues...
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Quote:

joeld wrote:


This is where I'm not sure if your 87 and my 89 has the same wire colors.

Joel


That's a good question Joel. If pressed for an answer, I'd think they're at least close, but who can say until they sit down with both manuals and compare.
Posted on: 2015/4/1 21:39
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joeld Re: Code 33 Saga Continues...
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Any luck?

Joel
Posted on: 2015/4/8 14:30
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bogus Re: Code 33 Saga Continues...
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There is a chance the 87 and 89 colours are the same, but I do have the 87 manual, let me do some digging... tonight or tomorrow, depends on time.
Posted on: 2015/4/8 16:38
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istter1 Re: Code 33 Saga Continues...
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it is the blue wire
check voltage at maf sensor wire it is on that chart the voltage is also
if it is higher than the reading the problem is in the maf sensor. The computer and the relay plugs didn't make any difference. They all worked great in my 87
good luck fixing mine took over 3 months at a friends shop that drove him nuts
Posted on: 2015/4/9 4:15
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CorvetteBob Re: Code 33 Saga Continues...
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Quote:

joeld wrote:
Any luck?

Joel


Thanks for asking. "istter1" sent me an ECM and a couple relays. Using the ecm, I was able to determine that both were operating the same, so I'm considering them both good for now.

I haven't had time to mess with the car, but if I can get thru the other stuff I've got ahead of me, I see what I can find this weekend.

That's about all I have for now.
Posted on: 2015/4/10 21:35
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istter1 Re: Code 33 Saga Continues...
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feels endless
Posted on: 2015/4/10 23:35
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CorvetteBob Re: Code 33 Saga Continues...
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I was just re-reading the thread. I think I need to clarify the year of my car.
It's an '86.
I mention this because I don't want any confusion about the color coding of the wiring. Years ago, Chevy used the same color wires year in/year out across model lines. Somewhere before the C4's showed up, they started changing things year to year. Not sure why, but, obviously, that's what we got.
Posted on: 2015/4/11 14:33
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CorvetteBob Re: Code 33 Saga Continues...
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i have a fairly decent rapport w/ the corvette tech guy at a local dealer. I spoke with him and his advice is a simple fix. Just sister in a new wire from the relay to the MAF. His reasons are simple.
1) Rather than taking the time to remove the run from the entire harness, it's obviously MUCH quicker to just add a wire and hide it the best you can.
2) by digging out the old wire, you're gonna have to move those 30 yr old wires around, and risk breaking the insulation, and that's a bad thing.

I guess now, that's exactly how I'm gonna do it. Running the new wire isn't hard, but my hopes are to disassemble the MAF plug to solder the new wire to the connector.

Do any of you guys know how to disassemble the MAF plug? I've been attempting to, but no luck. Normally they can be probed w/ a wire or needle to depress a tang on the connector. So far this method has not worked. Any help here?
Thanks in advance........

Posted on: 2015/4/18 14:09
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joeld Re: Code 33 Saga Continues...
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Depending on the condition of your connector, here is the quick easy way.

http://www.eficonnection.com/eficonne ... emDetails.aspx?ItemId=287



Joel
Posted on: 2015/4/18 18:30
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istter1 Re: Code 33 Saga Continues...
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Quote:

joeld wrote:
Depending on the condition of your connector, here is the quick easy way.

http://www.eficonnection.com/eficonne ... emDetails.aspx?ItemId=287



Joel


I used the same plug when checking connections and wires ran separate lines to do what you are attempting to do good luck . mine was something else
Steve
Posted on: 2015/4/18 18:54
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CorvetteBob Re: Code 33 Saga Continues...
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Quote:

joeld wrote:
Depending on the condition of your connector, here is the quick easy way.

http://www.eficonnection.com/eficonne ... emDetails.aspx?ItemId=287



Joel


Thanks Joel, but after a lot of trying, I can't get to any instructions on assembly of those connectors.
Posted on: 2015/4/18 19:41
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joeld Re: Code 33 Saga Continues...
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And that's the purpose of the pig-tail, to just splice into the harness by crimping or soldering.

Joel
Posted on: 2015/4/18 23:39
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CorvetteBob Re: Code 33 Saga Continues...
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Quote:

joeld wrote:
And that's the purpose of the pig-tail, to just splice into the harness by crimping or soldering.

Joel


You are absolutely correct, however I don't want to splice ALL five wires. Besides, I've already got a pigtail and used robbed it for the purple wire it had. I searched high and low for a repair connector w/ correctly colored wires, but couldn't find one.

But with that said, the repair has been made. As I was preparing to run the new wire, I was removing the old tape GM used to hold the harness together while constructing it. Apparently in this Corvettes early days, someone place a crimp connector several inches from the plug in the purple wire only. It was this aged connector that had gone bad. I replaced it and the "Code 33" is no more.

Case Closed
Posted on: 2015/4/19 1:46
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joeld Re: Code 33 Saga Continues...
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Congrats!! Good job.


Joel

Posted on: 2015/4/19 2:51
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Matatk Re: Code 33 Saga Continues...
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Nice find! Good place for others to look in the future if they have a similar issue. You never know what will crop up.

Apparently in this Corvettes early days, someone place a crimp connector several inches from the plug in the purple wire only. It was this aged connector that had gone bad. I replaced it and the "Code 33" is no more.
Posted on: 2015/4/19 12:36
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