MParks

Good afternoon!

Ive been having trouble with a code 33 problem, limp mode sucks when your an hour away from your house.

I found this blue wire and it looks to go to the ECM? Dont know if it has any real purpose but i want to be sure.

I figure my issue is wiring because ive searched all up and down these threads from people saying relays to replacing ECMs and trouble shot the sh*t out of my car for the past 2 weeks so right now im looking for loose grounds/wires that might cause a problem and only found a couple.

Also what are the grounds behind the motor for?

Twin_Turbo

iTrader: (25)

I have the same wire, it was taped away but it is a ground. I don't remember taping it away myself, I think it's a factory taping job.

Here's mine, the blue one is still taped away in this pic. The black is another ground (for the hood light) BTW, I have an 87 TPI too (350)



The grounds on the cyl heads are the main system grounds for the ECM & electrical system. There's also a ground strap to the firewall.

My car wouldn't fire the injectors when cranking, there was no cranking signal. Everything was new, I did some custom wiring (ign. boxes) and it all checked out. I reconnected the blue ground at the same spot as the black one and the car started and ran fine. Next day it didn't, MSD dizzy is shot. I think it was a coincidence that it started working right after I grounded the blue wire. I couldn't even find the wire in my electrical supplement (factory 87 service manual)

Twin_Turbo

iTrader: (25)

BTW, coed 33 is a maf code. Replace the maf power relay & burnoff relay. Might want to try cleaning the MAF first

MParks

Thats the way i found this one to, it was taped to the harness with the factory tape still on it, when i was digging into my wiring i glanced over and saw it. Very weird, so it makes me think maybe it could be part of my problem if not i might as well hook it up and see what happens. It sounds pretty important by your past situation with it. Ill hook mine up in the same spot as yours. Seeing as its a possible system ground it would have something to do with the MAF? Gotta love TPI

Thanks for the quick info!

MParks

Well, i replaced the MAF power relay with one a friend of mine had, and the burn off looks to be working because i can hear the "tick" and the fine wires glow red inside the MAF. Dont know what else it could be. I took a multi meter to everything as said on all the threads here on TGO so im pretty lost

Twin_Turbo

iTrader: (25)

I connected my blue wire to ground, thinking it was causing my issue. Nothing stared burning or smoking and it's still connected. I'll try and find out what this wire is. Maybe it's something fir a manual car?? Mine's an auto, what was yours originally?

My 88 5 speed doesn't have the blue wire taped up there. Haven't checked my 88 L98 auto

MParks

Ok let me know if you figure out what it is, and ya maybe? because im pretty sure our cars came with these access wires and connectors for the 5 speed option? I think. If your 5 speed doesnt have it then thats just weird, unless its connected somewhere else?

mine was orginally an automatic but then i swapped it out to a T56 just recently

Twin_Turbo

iTrader: (25)

My 5 speed is a bare bones only perf. options car, all the connectors for the AC and such are there, just factory zip tied out of the way. Wouldn't surprise me if they did something similar with the blue wire.

MParks

I hooked it up took it for a drive and the car went into limp mode again, so much for that! I still wanna know what that wire is for though ive done a lot of searching and simply couldnt find out what it is?

86blackiroc

iTrader: (12)

What do you mean by "limp mode"? Just a minor lack of power, or almost not willing to accelerate?

MParks

Just not willing to accelerate, the car will drive fine for about 5-10 minutes then itll go into this code 33 limp mode and when i hit the gas itll sputter and bog. At idle its 500rpm.

It was an intermittent problem before and now i cant drive it down my street without it happening. Ive searched ALL the threads here on the board and tried all of it besides replacing the relays. The burnoff is working. I switched my old MAF power with a spare used one and hasnt cured the problem.

One thing i remember is when a vacuum line came loose on my car at the throttle body it would always make a "hissing" noise before i shut off the car. I hooked it up a long time ago, but i unhooked it again to see if there was any vacuum and there wasnt? i checked my vac lines and they are all intact so i dont know what the deal is with the low vacuum? Possibly clogged? I would imagine that would set off a different code though

86blackiroc

iTrader: (12)

I think we both have the exact same problem then. I've been chasing it for years. Just about everything has been changed/swapped/modified except for the TPS and the engine wiring harness. A speed density swap is sounding appealing right now.

MParks

Tell me about it, for years?? I cant take 3 weeks of this crap!

86blackiroc

iTrader: (12)

Yep, years

It wasn't so bad when the car was stock, it would just lose a little power and throttle response. Then after the built 350tpi was installed (and custom chip), it would be basically not drivable when it would act up. But it would only do it if you started driving the car before it went into closed loop, so it was avoidable.

Then came the T56. For some reason, it would act up whenever if wanted to. No rhyme or reason to any of it. So I then had the chip modified for use with the manual tranny, and had the code 33 disabled completely. It was fine and dandy for a couple months, then out of the blue, it started freaking out again. I really can't drive the car at this point. Hopefully one of us will figure something out

MParks

I hear you on that, its pretty frustrating. I cant drive mine either, how are your relays looking? Question, do you have to replace ALL the relays (Burnoff and Power) ? it looks like they are all connected together in the harness.

From what i read most people are fixing their problems by replacing the relays, cleaning MAF, or have found something in the wiring which i havent. So im going to try relays and see what happens. I think faulty relays will cause intermittent problems for awhile before they just die.

89-bird

I was reading the posts and got curious about that wire myself and I went and looked just before typeing this and my '89 2.8 Firebird 5- speed has the wire on it also tapped . So not just the TPI cars have that wire .

MParks

If we get the answer to the mysterious blue wire and my code 33 problem this will be a successful thread!

I went out and tested my TPS again, because i had someone else adjust it since at the time i didnt know how to.. i backprobed it and it was reading .63VDC at idle!!! shouldnt it be .54 from what i read? If thats causing my code im going to be embarrassed.

Twin_Turbo

iTrader: (25)

yes around .54

MParks

So ya, it was my TPS.. how embarrasing is that Just for anyone who searches with these probs

86blackiroc

iTrader: (12)

Well dang, I've already checked that on mine. Glad you got yours fixed though

89-bird

Good to hear you got it running right , now for the wire identification .

87IROC-DAN61

Hello Twin_Turbo, and MParks!!

I have two 1987 Camaro's with 305 TPI, 5 speed, and no A/C, and this blue wire is connected to the same ground spot (G115) as the underhood lamp!!

I haven't figured out what it's for yet either, but I'm still looking!!

Tomorrow, I'll check my 1989 Camaro with 305 TPI and 700R4 to see if it's an auto/manual difference!!

86blackiroc

iTrader: (12)

Could it be used for something only on the non-AC cars maybe?

87IROC-DAN61

Hello All!!

I checked my 1989 Camaro with 305 TPI, 700R4 and A/C, and this wire is not at the ground spot (G115) as my other Camaros above. There is, in the same area, a blue and a green wire connected to the A/C system though, and this may be the answer!!

I'll keep looking for the correct answer, and not just an educated guess!!

89-bird

It should be taped at the blower motor like on my car and MParks car and Twin_Turbos car if you have it .

Pocket

iTrader: (24)

Of the 80 or so 3rd gen harnesses Ive disassembled, it's never been grounded. It's tied into the AC wiring, my guess is some sort of diagnostics for the circuit

MParks

Hey guys, i hate to say my car is playin tricks on me. Went out cruising yesterday, about an hour drive to my destination and back. I got there just fine, about half way back my car set a code 33 again. Man was i pissed. adjusting the TPS helped for those couple days any ideas?

Im glad to see people are looking into this blue wire ordeal, i hooked mine up with no results.

MParks

Heres what i found, theres a ground strap that goes from the firewall to the back of the block on the passenger side. It also has two ground wires coming from the same harness as the burnoff, power for the MAF. If those grounds were loose, that would cause an intermittent problem right? Besides that, the bolt that they were on was loose coming out of the block so i tightened it, put a nut over it because there wasnt one thats why they were loose. What do you guys think?

87IROC-DAN61

Hello 89-bird!!

This blue wire is grounded at (G115), which is the same grounding spot as the underhood light wire on my two 1987 Camaros without A/C, but on my 1989 Camaro with A/C it's not there!!

Hello Pocket!!

It's strange that you haven't seen this wire grounded at (G115) before, my two 1987 Camaros are bone stock, and one of them I've owned for 22 years + !!

My two 1987 Camaros are made in different factories also, one in Norwood, and the other in Van Nuys, yet they are both built with that wire grounded at (G115) with the underhood light!!

89-bird

That could have been the problem . Also I have seen cars do strange things with bad ground connections . I worked at a shop and a boy that worked there was trying to fix a Caddy and all signs pointed to a bad ECU and he put in a new one and the problem was still there and another mechanic and I asked if he checked all the grounds and he said he did and we told him there were other ground locations and he went to check the others and the ones located under the passenger kick panel were corroded and a little loose . He cleaned and tightened them and that fixed the car . Long story short always check the connections when having a problem .

87IROC-DAN61

Hello All!!

The blue wire is for the A/C system's "Fan Control Switch" (Pressure Switch), if however, you don't have A/C, the blue wire gets grounded, and the closest ground, without using a new ground point or a new bolt, is the underhood lamp ground (G115) point.

It seems that either a "TSB" or a "rethink" of the need for it to be grounded led to the wire eventually being just taped off, as opposed to being actually grounded!!



P.S. I found this circuit diagram in a Haynes Manual from 1987 in the new supplement: Revisions and information on 1985 through 1987 models. It covers the 2.8, 5.0, and 5.7 engines with the same explanation!!

ECM pinout C9 for the 2.8, and ECM pinout D11 for the 5.0, and the 5.7!!

The underhood wiring harness's for the non A/C cars had all the connectors for the A/C system, (at least mine do) and makes it cheaper for GM to produce due to commonality of parts thinking!!

Twin_Turbo

iTrader: (25)

I figured out what the blue wire is. I had an issue w/ my 87, the ECM controlled fan would be running as soon as there was a distributor reference pulse. Decided to pull the wire and see what happens and whaddayaknow.... without it grounded the fan doesn't come on, as soon as it's grounded whammo... dr. side fan on. It may be part of the wiring for a single fan setup then.

89-bird

That would go with what 87IROC-DAN61 said about it being for the fan control on A/C cars and it gets grounded on the non A/C cars .

87IROC-DAN61

Twin_Turbo

iTrader: (25)

I'm probablt fonna wire a roggle swithc in it so I can manually activate the fan. This is much better than all the hack jobs you see so often