sxerob
Forum Newbie
Posts: 43
Reg: 07-08-12
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07-09-12 11:55 PM - Post#2246437
Hello,
First post here. Seems to be a good resource so far, so thanks!
I recently resurrected my first car, a '92 K2550 Suburban - 454 7.4L. My dad bought this old dog new in 92 and I drove it during high school. I recently inherited the title after it had sat for eight years and I got her running as my daily driver in Dec.
My reason for posting today is that I ran a diagnostic code checker on the thing this morning after a service engine light and pulled a code 43 - ESC Module. Having no idea what this is, I researched it in the Haynes manual. I was then told by my local O'Reily that the part doesn't exist anymore and I have to replace it with a new ECM. Is this true? Also, how difficult is the repair to do at home? A "reprogramming" of the ECM was mentioned while in store which made me think I had to take it to a mechanic.
Also, I have interesting issues with the tail lights. I recently changed the brake switch unit and fuses to get the brakes to function again however, now I dont have running lights. Research tells me that the multi-switch might be the issue as the running lights are bridged in that switch. Any intel?
Thanks, in advance.
Robert
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 someotherguy
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Age: 43
Loc: Texas
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07-10-12 05:03 AM - Post#2246466
In response to sxerob
Welcome to Chevytalk, Robert,
It sounds like you may want to begin by no longer taking advice from that particular O'Reilly's employee. 
Your code 43 should actually be for the knock sensor. The most common cause for code 43 is the connector has simply come off the sensor as it's in kind of a vulnerable area, and the plastic shroud portion of the connector can get brittle, too. The knock sensor is mounted low on the block, just ahead of the starter. Your 7.4 engine may have dual knock sensors with another one on the driver's side, similar location on the block.
Sometimes the knock sensor itself is bad, not uncommon at all. If you replace it be sure you get the one spec'd for your year/engine/trans as there are different calibrations for them, and be sure to replace it on a cold engine as it is in contact with the coolant passages - usually you'll get some coolant draining out when you remove it, unless there's a ton of deposits/crud built up in the bottom of the block.
Finally, you can get a false code 43 if the base timing is too far retarded (the ECM's test is to momentarily advance timing enough to intentionally cause a knock, to see if the sensor registers it) - on the 7.4 I think it may be 4 or 6 degrees BTDC; check the emissions label on your fan shroud. To accurately check timing on your TBI engine you should have it fully warmed up, then disconnect the tan/black bypass wire (locations listed in the FAQ post but you'll find it on the passenger side firewall for '92), adjust timing as needed, then hook the wire back up.
Did you have the running light problem before you did the other work to get the brake lights working, or after? If before, a common cause is the headlight switch has gone bad. Try jiggling it on/off numerous times to see if the running lights come on at any point. I assume since you've been into the fuses you've checked them all to be sure there aren't other ones out?
Also, check the ground wire for the taillight harness; you should find it on the driver's side of the frame rail near the back of the truck. Single black wire bolted to the frame.
Richard
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sxerob
Forum Newbie
Posts: 43
Reg: 07-08-12
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07-10-12 09:26 AM - Post#2246545
In response to someotherguy
Thanks for the great reply, Richard!
I thought that the knock sensor (ESC from what I read, am I wrong with that?) was on the top right of the block close to the firewall.
Here is where I thought it was: 
Anyway... being next to the starter makes sense as I changed the started about a two months ago and that seems to be when the service light came on. I will get down there again and poke around. Is there something to this guy saying that the knock sensor is out of production? Usually, there is one guy at my O'Reily that is really helpful but he wasnt there yesterday (obviously why I only walked out with a fuel filter).
I didn't have any lights in the rear before this. There is an alarm on the car that seems to be causing some wonky issues. That being said, the brake lights working was a big step and they seem to be operating as normal.
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someotherguy
Moderator
Posts: 23378
Age: 43
Loc: Texas
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07-10-12 09:45 AM - Post#2246557
In response to sxerob
The rectangular plastic item hanging off that bracket is your MAP sensor, which tells the computer what the vacuum reading in the engine is. Unrelated completely to what's going on.
Don't let what the parts guy told you confuse the issue. It may be fact that the ESC module isn't available as a new part from O'Reilly's but again that isn't what your code 43 is about. The ESC module is not the knock sensor.
Knock sensors are readily available at any parts house. But check the connection & wiring first. It's possible you bumped the connector off when doing the starter as it's very easy to hit the sensor.
Richard
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sxerob
Forum Newbie
Posts: 43
Reg: 07-08-12
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07-10-12 10:19 AM - Post#2246571
In response to someotherguy
Ok cool... I'll give it a shot and let you know what happens. Thanks again!
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355Cheyenne
Senior Member
Posts: 3743
Loc: Northern MN
Reg: 10-27-04
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07-10-12 11:22 AM - Post#2246597
In response to sxerob
Maybe I missed it but incase richard missed, when you pull the knock sensor it is actually a block plug. Before knock sensors they just put a bolt as a plug as a means to drain the block of coolant.
What I am saying is that when you pull the sensor coolant is going to start pooring out. If you have to replace the sensor make sure you have it on hand before pulling the old one. If you are quick you shouldn't loose much coolant at all.
| 98 Silverado k1500 4x4 350 |
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sxerob
Forum Newbie
Posts: 43
Reg: 07-08-12
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07-10-12 03:01 PM - Post#2246690
In response to 355Cheyenne
Ah... so that's why they said to drain the coolant. Thanks, I was trying to put those two dots together. Truthfully, I should probably change many of the fluids anyway so that might not be such a bad thing.
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454cid
Contributor
Posts: 297
Age: 40
Reg: 02-18-12
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07-10-12 03:30 PM - Post#2246704
In response to sxerob
Ah... so that's why they said to drain the coolant. Thanks, I was trying to put those two dots together. Truthfully, I should probably change many of the fluids anyway so that might not be such a bad thing.
And power wash that engine, it's filthy!
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sxerob
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Posts: 43
Reg: 07-08-12
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07-10-12 03:37 PM - Post#2246706
In response to 454cid
HAHA... Tell me about it, man. Since it was sitting for so long a bunch of mischievous critters found their way in there... I am nervous to pressure wash the thing for fear of knocking a bunch of crap loose that would cause more problems. A buddy mentioned steam cleaning the thing. Anyone have any insight?
I am working on finishing a motorcycle right now and I have a bunch of paint/powder and blasting gear at the house. When I button the bike up, I plan on making the inside a bit more pretty.
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454cid
Contributor
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Age: 40
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07-10-12 06:28 PM - Post#2246767
In response to sxerob
HAHA... Tell me about it, man. Since it was sitting for so long a bunch of mischievous critters found their way in there... I am nervous to pressure wash the thing for fear of knocking a bunch of crap loose that would cause more problems. A buddy mentioned steam cleaning the thing. Anyone have any insight?
I get engines wet all the time. The only thing I avoid are stickers, as they can come off eventually. The only vehicle I had any real trouble with was an 81 Chevy LUV (really an Isuzu). I'm guessing the plug wires were old.
If you have a self serve car-wash that eats quarters and has a decent degreaser, that would be a good place to start. The only bad thing, would be that if you do have troubles, you're at a car wash and not your driveway. You could take a can of WD-40 and a screw driver, just in case. That way you could spray the distributor if you needed to. I doubt you'd need to, Though.
I think your engine would have to be super dirty before paying for someone to steam clean it would be necessary...... assuming that's not something that you had access to yourself. For about a month I had an old International with a Detroit Diesel 2-stroke..... THAT needed to be steam cleaned!!! I tried power washing it, and about all it did was knock the dust off and peel some paint. Some heavy gunk did end up in the gravel driveway, but most stayed on the truck.
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sxerob
Forum Newbie
Posts: 43
Reg: 07-08-12
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07-11-12 09:58 PM - Post#2247253
In response to 454cid
So I got a few things done tonight. Changed the fuel filter, which I could barely blow air thru. While I was down there I took a look at the knock sensor and sure enough, the wire for the sensor was hanging off. Put that back on and the light went off! Thanks, Richard!
Also, the female end of my seatbelt on the passenger side was busted. I ordered a universal kit from JC Witney and went to install it today... It's a three bolt system that looks like this:
Not sure if anyone has had any success with these. Doesn't seem like a plug and play fix with the bolt configuration that exist. The good news is that the plug from the kit works with the stock belt. Only thing is that the kit was $100 and I would like to get the whole thing replaced, if possible.
Edited by sxerob on 07-11-12 10:01 PM. Reason for edit: No reason given.
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sxerob
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Posts: 43
Reg: 07-08-12
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07-12-12 10:27 AM - Post#2247409
In response to sxerob
Woke up this morning and the service light was on again... Took a look and the wire was hanging again. I would like to splice in a new one so the connection will be more sturdy. I did a search but only found the actual sensor, not the wire itself. Is that available somewhere?
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tardisguy
Contributor
Posts: 120
Age: 28
Loc: San Antonio, TX
Reg: 09-15-10
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07-12-12 12:09 PM - Post#2247446
In response to sxerob
time to go junkyard hunting. If they are nice guys at the junkyard and thats all you get they might just give it to you. otherwise it will probly only be a buck or two. There are tons of them, they should all be the same on all chevy v-8's big or small block.
Andrew
91 Chevy C1500 ext cab, TBI 350 auto, 2in suspension lift. (DD)
86 Chevy M C SS, auto 305 with port and polish, Flowtech Afterburner headers, duals to Jegs chambered mufflers (Weekend toy/project)
2012 Mitsu Outlander Sport (wife's DD) |
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sxerob
Forum Newbie
Posts: 43
Reg: 07-08-12
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07-12-12 12:34 PM - Post#2247458
In response to sxerob
I had a feeling that would be the deal. I should go there anyway to look for some other things.
So about these running lights...
I got the brake lights to work but I have no rear running lights. Changed the whole assembly a few months back so the bulbs etc aren't the issue. Have blinkers, brakes and back ups running. When I hook it up to a boat trailer, the trailer has running lights. I have heard about the multi/cruise control switch being an issue... is there anything else Im not aware of?
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someotherguy
Moderator
Posts: 23378
Age: 43
Loc: Texas
Reg: 08-01-03
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07-12-12 03:20 PM - Post#2247512
In response to sxerob
You can get that knock sensor pigtail at most auto parts stores. Sometimes they can be really proud of them, so be prepared for a small amount of sticker shock. Considering what I've seen most knock sensor connectors look like, I'd buy a new one instead of trying for used on this particular item. I just looked it up on NAPA's website and was surprised "knock sensor" didn't turn up any results; they have it listed under "detonation sensor" which is funny. Everyone calls 'em knock sensors, and that's how they used to always be listed. Anyway a DETONATION sensor connector at NAPA is $13.49
On the lights...how is your trailer harness connected? It may actually be part of the problem. Some T in at the connection between the truck's harness along the frame and the separate taillight harness section, but usually they're just hacked in with a bunch of splices, or worse. I'd investigate that area really close, and consider disconnecting the trailer harness for further troubleshooting on the factory portion of the wiring.
Richard
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454cid
Contributor
Posts: 297
Age: 40
Reg: 02-18-12
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07-12-12 07:52 PM - Post#2247598
In response to someotherguy
....I just looked it up on NAPA's website and was surprised "knock sensor" didn't turn up any results; they have it listed under "detonation sensor" which is funny.
That doesn't surprise me at all. NAPA's website is absolutely horrible. It's worse than Advance Auto, which is bad enough.
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sxerob
Forum Newbie
Posts: 43
Reg: 07-08-12
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07-12-12 11:20 PM - Post#2247660
In response to someotherguy
NAPA had one. Spliced the wire and got it on. Lights out and the part is on.
Here is the old, busted part:
I thought that the sensor wire would solve another issue I am having but unfortunately, I was wrong. When I am running low on gas, say about a 1/4 of a tank left, my idle is fairly unstable... sometimes even getting below 1000rpms and dying. I replaced the fuel filter yesterday thinking that would make a difference and although it helped in other areas, it did not fix this issue. If the car has more than a 1/4 of a tank, it runs with out any issues. As soon as it gets to that range, it bogs at idle and sometimes off the line. Now I am thinking I need to clean the throttle body. Any way I can test this? What else could it be, O2 sensor?
Thanks in advance.
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someotherguy
Moderator
Posts: 23378
Age: 43
Loc: Texas
Reg: 08-01-03
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07-13-12 05:56 AM - Post#2247711
In response to sxerob
Driveability symptoms that are consistently tied to the fuel level in the tank are unlikely to be caused by anything at the throttle body.
It's possible the pump is getting weak, or more likely, the short section of rubber hose between the pump and the hard line on the sender has some tiny cracks or pinholes in it. The hose deteriorates with age and constant immersion in the fuel.
It's also possible, not very likely but it does happen, that the plastic tray inside the tank has broken or come loose. It acts as a baffle for the fuel pump so that it doesn't starve for fuel under maneuvering.
The lower the fuel level in the tank, the more the things in the previous two paragraphs are going to show themselves. My suggestion would be, until it's really time to drop the tank (not a lot of fun) try to keep it at 1/2 tank minimum or better. This is good for the pump too as the fuel acts as a coolant for the pump.
Richard
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sxerob
Forum Newbie
Posts: 43
Reg: 07-08-12
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07-13-12 10:06 AM - Post#2247787
In response to someotherguy
Well, crap. I was hoping you wouldn't say that. I had to drop the tank to replace the fuel pump to get the thing started after it was sitting. The hose was completely eroded. The whole unit was replaced except for the siphon bag (didn't come with the kit and was told it was ok), which I thought might become an issue. Either that, or it actually fell off... bummer. You're right, dropping the tank is no small task. It's very cumbersome.
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someotherguy
Moderator
Posts: 23378
Age: 43
Loc: Texas
Reg: 08-01-03
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07-13-12 01:30 PM - Post#2247854
In response to sxerob
OK, then in that case the hose shouldn't be suspect unless it was a super cheapo pump that came with an inferior grade of hose. New pumps come with a piece that should be appropriate for use in fuel.
Did you notice the plastic tray inside the tank I was talking about? It's situated on the floor of the tank so that the pump/sender assembly sits down inside of it.
Who told you it was OK to not replace the sock? They should always be replaced with the pump; they're inexpensive and usually they get ripped up anyway trying to remove them from the old pump. This is your very first line of defense on filtration so it's pretty critical.
Richard
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sxerob
Forum Newbie
Posts: 43
Reg: 07-08-12
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07-13-12 01:36 PM - Post#2247857
In response to someotherguy
I wasnt looking for a plastic tray but I did notice that there is a square area that the pump sits inside of. Is that what you are referring to? It's the 42 gal tank, not sure if that changes anything.
I forget which store I purchased it from but they said that the siphon bag should be good. I raised my eyebrows but... maybe it was because they didn't have one. I think I bought Bosch pump too. Cant remember, it was about over 6 months ago and I have purchased quite a few things for this truck.
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someotherguy
Moderator
Posts: 23378
Age: 43
Loc: Texas
Reg: 08-01-03
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07-13-12 01:44 PM - Post#2247865
In response to sxerob
Yeah, that's classic "it'll be fine (we don't have it in stock)" mentality of subhuman parts house employees, since real parts men are nearly extinct. 
Bosch is OK; I've used one or two of their pumps, though I prefer to use Delphi or AC Delco these days.
The square area is what I'm talking about. If it appeared unbroken, and not loose inside the tank, then it's likely fine. Every once in a while the fasteners that hold it to the tank floor let loose or the tray breaks away from them.
Richard
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355Cheyenne
Senior Member
Posts: 3743
Loc: Northern MN
Reg: 10-27-04
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07-13-12 10:14 PM - Post#2248006
In response to someotherguy
I had a very similar issue and to be honest I am not entirely sure about the mechanics of it but it all wound down to that stupid plastic tray. Basically you have a plastic tray sitting on the bottom with 4 metal pins that guide it and it is supposed to float I think to some extent, the pump and sock keep it from floating off the pins that only go up so far. This is going back a decade almost now but I think the new pump was a little different and the tray was able to work off a little so that it wasn't holding fuel and acting as a "baffle". I think I fixed it by bending the pins a little to keep it from floating so high and to fall off the pins, because the new pump was a little shorter...
Did I make any sense?
| 98 Silverado k1500 4x4 350 |
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tardisguy
Contributor
Posts: 120
Age: 28
Loc: San Antonio, TX
Reg: 09-15-10
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07-14-12 08:33 AM - Post#2248101
In response to 355Cheyenne
the new hose might be leaking from one of the ends so the same thing is happening as when the hose was cracked
Andrew
91 Chevy C1500 ext cab, TBI 350 auto, 2in suspension lift. (DD)
86 Chevy M C SS, auto 305 with port and polish, Flowtech Afterburner headers, duals to Jegs chambered mufflers (Weekend toy/project)
2012 Mitsu Outlander Sport (wife's DD) |
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Biomedtech
Forum Newbie
Posts: 44
Reg: 01-18-11
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07-16-12 08:01 PM - Post#2248930
In response to tardisguy
Just another to check for the driveability issue would be....
I had a similar issue with poor idle and it turned out that the passage in the throttle body where the PCV connects was completely plugged with crap. Cleaned it out and it idled beautifully!
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sxerob
Forum Newbie
Posts: 43
Reg: 07-08-12
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07-17-12 10:15 AM - Post#2249089
In response to Biomedtech
I'm going to try to clean the throttle body and see if that makes any difference. I doubt it will but I should do that anyway. I just want to do all I can before I have to drop the tank to see that I did something stupid like not put the screen on properly or clamp the hose down... dropping the tank is just such a pain in the censored, especially when you've dont it 3 times in the last 6 months.
On a bright note, I had the detailing company at my work steam wash my engine bay. It was dirty enough to pay someone to do it the first time. Now the only thing that is super obvious is the corrosion on my block and a few other areas. Some of the things I can get to easily... others not so much. Here are a few shots.
More on the other issues this week, I'm sure. I have to do a bunch of things to get ready to tow a boat.
Thanks for all of the suggestions, guys. I appreciate it.
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355Cheyenne
Senior Member
Posts: 3743
Loc: Northern MN
Reg: 10-27-04
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07-17-12 01:10 PM - Post#2249148
In response to sxerob
Not to distract you but time for a new radiator cap while you are at it.
| 98 Silverado k1500 4x4 350 |
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sxerob
Forum Newbie
Posts: 43
Reg: 07-08-12
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07-19-12 09:34 AM - Post#2249879
In response to 355Cheyenne
I need a few things for this beast, not just a radiator cap
Reading more and more about this issue. It seems to be happening earlier on in the fuel tank "cycle" and by that I mean with more and more fuel in the tank, still with only with less than a half a tank.
This weekend I am going to clean the throttle body in its entirety, see if that helps at all and then drop the tank.
One thing I keep reading is a bad O2 sensor, however, I would think that would trip a service light. Any insight?
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tardisguy
Contributor
Posts: 120
Age: 28
Loc: San Antonio, TX
Reg: 09-15-10
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07-19-12 11:13 AM - Post#2249908
In response to sxerob
if in doubt, swap it out. It cant hurt
Andrew
91 Chevy C1500 ext cab, TBI 350 auto, 2in suspension lift. (DD)
86 Chevy M C SS, auto 305 with port and polish, Flowtech Afterburner headers, duals to Jegs chambered mufflers (Weekend toy/project)
2012 Mitsu Outlander Sport (wife's DD) |
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355Cheyenne
Senior Member
Posts: 3743
Loc: Northern MN
Reg: 10-27-04
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07-19-12 12:20 PM - Post#2249921
In response to sxerob
The ECM in the 95 and down is really bad at detecting "lazy" o2 sensors. If old or not sure then just replace.
| 98 Silverado k1500 4x4 350 |
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