brocktice
New member
There are a lot of threads on ADD troubleshooting here and some of them have helped me in the past. I just finished troubleshooting another perplexing issue and I want to share what happened so that maybe it will help someone else.
My 94 T4R had a problem with 4wd not engaging when I bought it about two years ago. Some quick troubleshooting showed me that the hoses to the VSV were swapped. Easy fix.
Fast forward two years, I've had an engine and transmission swap, both done by shops, not me. Today I was driving down a sandy dirt road and decided to flip on the 4wd, and the light didn't come on.
I checked the VSVs, they had vacuum and were switching appropriately. I tried swapping, I checked that the hoses were going to the right places. Everything checked out, still didn't work.
I tried hooking the 4wd hose directly to the check valve, because it seemed stronger, and the 4wd engaged. I thought maybe my VSV was clogged or something, but before I ordered the part I decided to troubleshoot a little more to make sure.
I unhooked the 4wd hose (the one that comes up from the actuator and connects to the blue VSV) and blew on it. I was able to keep blowing air through and heard a hiss from near the engine.
I unhooked the 2wd hose (brown vsv) and blew, no air moved.
As a sanity check, I unhooked the 4wd hose from the actuator and plugged that end, then I blew into the VSV end. Hiss. My brother in law got under the truck and quickly found that the hose had been allowed to rest against the front diff and melted, opening a hole.
(EDIT) I was rather concerned that the diff could have gotten that hot. Further inspection revealed the bolts/flanges of the CV axle are rubbing against the hose. I'll have to route this more carefully once my new silicone hoses arrive. (END EDIT)
I guess I'm going to be picking up some vacuum hose. This is a pretty easy sanity check but it took me a long time to arrive at it, so I hope this post can help someone else along.
My 94 T4R had a problem with 4wd not engaging when I bought it about two years ago. Some quick troubleshooting showed me that the hoses to the VSV were swapped. Easy fix.
Fast forward two years, I've had an engine and transmission swap, both done by shops, not me. Today I was driving down a sandy dirt road and decided to flip on the 4wd, and the light didn't come on.
I checked the VSVs, they had vacuum and were switching appropriately. I tried swapping, I checked that the hoses were going to the right places. Everything checked out, still didn't work.
I tried hooking the 4wd hose directly to the check valve, because it seemed stronger, and the 4wd engaged. I thought maybe my VSV was clogged or something, but before I ordered the part I decided to troubleshoot a little more to make sure.
I unhooked the 4wd hose (the one that comes up from the actuator and connects to the blue VSV) and blew on it. I was able to keep blowing air through and heard a hiss from near the engine.
I unhooked the 2wd hose (brown vsv) and blew, no air moved.
As a sanity check, I unhooked the 4wd hose from the actuator and plugged that end, then I blew into the VSV end. Hiss. My brother in law got under the truck and quickly found that the hose had been allowed to rest against the front diff and melted, opening a hole.
(EDIT) I was rather concerned that the diff could have gotten that hot. Further inspection revealed the bolts/flanges of the CV axle are rubbing against the hose. I'll have to route this more carefully once my new silicone hoses arrive. (END EDIT)
I guess I'm going to be picking up some vacuum hose. This is a pretty easy sanity check but it took me a long time to arrive at it, so I hope this post can help someone else along.
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