Did some diagnostics today and would like some feedback... (ABS & 4WD)
#21
12-06-2008, 08:03 AM
RE: Did some diagnostics today and would like some feedback... (ABS & 4WD)
Kyle-another question-just looked at another poster with an issue with a 96 int. tough start. Yesterday I had the same on a 96 also. 4.3, 97k, tuned up recently-fuel gauge ok, bla, bla, bla.....here's the question-decided to hang a new coil on it(ACDelco)-fired right up-no long 3-5 second-crank time-started the best I've ever heard it start. Then, being Mr ****-I hooked up the old existing coil-and whola, started 10 times perfectly. Question....now maybe I tightened or jiggled the plug or coil wire providing a better connection and that's is but....have you ever seen a coil cause prolonged starting time? It would start and run but just prolonged start/fire time. I'll possibly re-post(keep you posted) today is another day and in between things I'm going to play with it but as of last night, all was well with it. JP
#22
12-06-2008, 05:48 PM
RE: Did some diagnostics today and would like some feedback... (ABS & 4WD)
Yep, I know Rick. Good guy and he is still there.
Let me see if I can find a good picture of the bearing assembly. Well, not really a "good" picture, but hopefully it will be a good illustration:
I would much rather file on the cast iron bearing housing than risk messing up the WSS. When I did it, I just removed the WSS and used a scraper to get the loose junk off of the surface, then used some emry cloth to clean it up. If you use anything powered (like a dynafile), you just have to be careful that you do not file off too much. Clean it up, reinstall the WSS and the wheel (do not worry about the brakes) and then spin the tire while you monitor the ACmV output. If it is within the specs I posted earlier, you are done. If not, you need to file more.
Let me see if I can find a good picture of the bearing assembly. Well, not really a "good" picture, but hopefully it will be a good illustration:
I would much rather file on the cast iron bearing housing than risk messing up the WSS. When I did it, I just removed the WSS and used a scraper to get the loose junk off of the surface, then used some emry cloth to clean it up. If you use anything powered (like a dynafile), you just have to be careful that you do not file off too much. Clean it up, reinstall the WSS and the wheel (do not worry about the brakes) and then spin the tire while you monitor the ACmV output. If it is within the specs I posted earlier, you are done. If not, you need to file more.
#23
12-06-2008, 10:06 PM
RE: Did some diagnostics today and would like some feedback... (ABS & 4WD)
ORIGINAL: Peru Motors
with the automatic t/case there is no t/case switch-the firewall mounter unit basically takes the place of it. This will cost you nothing-if you want try it. I've had it work betcha 100 times. For how long-I can't tell you, I'm sure it varies but....Disconnect the neg. battery cable then the positive. Pull out one or the other battery bolt. Pull the pos. cable. Then touch both together using the one bolt as a 'bridge' to make sure they both make solid contact for 30-60 seconds or so. Then re-hook back up the positive first then the negative. Now try the 4wd-good luck as for the ABS-if you ohm out the wire on the suspected side and it's out of limits then that is your issue but if the wire is not bad I have had 3 Blazers/Jimmies in our shop in the last month where a scan tool showed(tech 2 tool) left or right side MPH readings 'dropping' out(skipping MPH reports) as I sped up and slowed down causing activation of the ABS. Tried cleaning all 3 of these vehicles to no avail. The fix ended up being a new Timken wheel bearing. If you have those same issues I bet you have a wheel bearing in your future-hey maybe Santa can bring you on but ask him for a good quality one or he'll be coming back to exchange it! Keep us posted .JP
with the automatic t/case there is no t/case switch-the firewall mounter unit basically takes the place of it. This will cost you nothing-if you want try it. I've had it work betcha 100 times. For how long-I can't tell you, I'm sure it varies but....Disconnect the neg. battery cable then the positive. Pull out one or the other battery bolt. Pull the pos. cable. Then touch both together using the one bolt as a 'bridge' to make sure they both make solid contact for 30-60 seconds or so. Then re-hook back up the positive first then the negative. Now try the 4wd-good luck as for the ABS-if you ohm out the wire on the suspected side and it's out of limits then that is your issue but if the wire is not bad I have had 3 Blazers/Jimmies in our shop in the last month where a scan tool showed(tech 2 tool) left or right side MPH readings 'dropping' out(skipping MPH reports) as I sped up and slowed down causing activation of the ABS. Tried cleaning all 3 of these vehicles to no avail. The fix ended up being a new Timken wheel bearing. If you have those same issues I bet you have a wheel bearing in your future-hey maybe Santa can bring you on but ask him for a good quality one or he'll be coming back to exchange it! Keep us posted .JP
As for the ABS, the hub is under warranty still, so I'm going to exchange it.
One last question that went unanswered though - where are the bolts/clips for the panel covering the TCCM? I'd like to check and clean up its connector, if possible (assuming the battery disconnect doesn't do it).
#24
12-08-2008, 01:37 PM
RE: Did some diagnostics today and would like some feedback... (ABS & 4WD)
So I tried resetting the electrical system by connecting the battery leads with no success. "Service 4WD" light still comes on immediately after pressing any of the 4WD buttons.
I inspected the TCCM - it appears to be fine. The bracket it mounts to had a bit of rust, but there was no apparent water damage to the TCCM itself.
I also pressed the 4Hi button and pulled the vacuum hose that goes to the actuator, expecting there to be vacuum - there wasn't any. Does this mean that the switch is not opening to allow vacuum to flow through?
One last question... is there any way I could manually bypass the switch not opening? For example, could I put a vacuum connector on the two hoses when I absolutely need 4Hi?
Any suggestions are greatly appreciated at this point - I'm going to try anything that's recommended and then it'll be going to Chevy next week if I can't figure it out... I need 4WD where I live (lots of fairly steep hills and the plowing isn't very efficient).
I inspected the TCCM - it appears to be fine. The bracket it mounts to had a bit of rust, but there was no apparent water damage to the TCCM itself.
I also pressed the 4Hi button and pulled the vacuum hose that goes to the actuator, expecting there to be vacuum - there wasn't any. Does this mean that the switch is not opening to allow vacuum to flow through?
One last question... is there any way I could manually bypass the switch not opening? For example, could I put a vacuum connector on the two hoses when I absolutely need 4Hi?
Any suggestions are greatly appreciated at this point - I'm going to try anything that's recommended and then it'll be going to Chevy next week if I can't figure it out... I need 4WD where I live (lots of fairly steep hills and the plowing isn't very efficient).
#25
12-08-2008, 07:17 PM
RE: Did some diagnostics today and would like some feedback... (ABS & 4WD)
no vacuum at the firewall/2 hoses connected to actuator??? This actuator/celonoid has vacuum to one side of it at all times and then when 4wd is requested it continues thru. If you don't have you should, I think in a previous post either here or another post, I looked at an 01 with the same set up to see which hose provides the vacuum all the time.(upper or lower) But if you indeed have none, that is a problem...I still don't think it would prohibit the light operation but who knows...You have to get vacuum there first and then we go from there. JP[
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#26
12-08-2008, 08:05 PM
RE: Did some diagnostics today and would like some feedback... (ABS & 4WD)
I have vacuum at the bottom, none at the top when 4Hi is pressed. I tried reversing it thinking perhaps I routed them wrong... it just made a continuous hissing (it clearly shouldn't have constant vacuum to the top) and didn't resolve anything, so I put it back to how it was.
#27
12-08-2008, 09:03 PM
RE: Did some diagnostics today and would like some feedback... (ABS & 4WD)
Sounds like the solenoid is not functioning properly. Take a test light and see if you get +12V at the connector to the actuator when in 4HI. If you do, then the actuator is bad.
#28
12-09-2008, 12:42 AM
RE: Did some diagnostics today and would like some feedback... (ABS & 4WD)
You're speaking about the solenoid on the firewall, correct? That would be annoying since that's the part I replaced after Chevy told me that was the source of the code. After replacing it to no avail, I figured it was something directly related to the solenoid. I'll check it tomorrow if the weather isn't bad.
#29
12-09-2008, 06:15 AM
RE: Did some diagnostics today and would like some feedback... (ABS & 4WD)
celonoid is probably not bad. No need to 12v test it if: vacuum to it(not 100% sure off hand top or bottom but you said bottom) in 2wd, idling-then when in 4wd vacuum goes thru it. If it does that or you can 'jumper' it to do that, then it's ok. Jerry[]
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#30
12-09-2008, 07:32 AM
RE: Did some diagnostics today and would like some feedback... (ABS & 4WD)
Yeah, I guess I had forgotten that you have already replaced that part. Check for power to the solenoid. If you are not getting vacuum pressure through it when in 4HI as you stated, then there is something wrong there.