having what seems to be a common issue with a lot of people and need some help the service 4wd light is on and there are no lights on the selector switch they cut on briefly when you crank the truck then right back off all the fuses test good had a code reader hooked up to it and it is the one that will read off the tccm but it says there are no codes on it to pull if some one has a pin out or something that i can look at to test voltage on the tccm or something that would be nice or any advice would be really helpful
1999 tahoe service 4wd light
- Thread starter b9127
- Start date
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bigfootchiro
Full Access Member
If I remember off the top of my head, that is usually an indication that the selector switch needs to be replaced. Haven’t researched it in a long while, but I think that’s the case.
east302
Full Access Member
Was that light new for 99? Can’t say I remember seeing it on my 98.
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Sent from my iPhone using Tapatalk
bigfootchiro
Full Access Member
I think it started in 96 with the cluster change, but not 100% sure on that. I know 98 has it.
I ordered a new one and replaced it the other day and still in the same boat
bigfootchiro
Full Access Member
Have you checked the actuator motor?
I had a new one and plugged the connector into it didn't put it in the differential just plugged it in to see if that helped and it did not
I found this it was extremely helpfull leading to find my tccm is bad hopefully it will help any one else reading this post
Chubbs
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you can test that switch bank with a voltage meter before you replace it. I know it doesn't help at the moment, but there are ways to go about diagnosing some problems before spending money/ removing & replacing/ so forth.
each 1 of the switches has a different voltage that should read within the engineered specs. there are multiple sources providing said specs that can be found on the internet and cited via YouTube tutorials.
fyi for others who may stumble on the thread.
@b9127 we appreciate your contributing the info which led to your successful repair. the attachment appears to be a typical diagnostic tree that can be found in various workshop manuals. I don't feel that we as "DIY community" stress enough the importance of owning different forms of technical literature.
you got @swathdiver telling everybody who posts a thread to get a TECH2, and there are a couple of threads discussing workshop manuals of both paper & electronic form. I wish they would make that a sticker for every subforum.
each 1 of the switches has a different voltage that should read within the engineered specs. there are multiple sources providing said specs that can be found on the internet and cited via YouTube tutorials.
fyi for others who may stumble on the thread.
@b9127 we appreciate your contributing the info which led to your successful repair. the attachment appears to be a typical diagnostic tree that can be found in various workshop manuals. I don't feel that we as "DIY community" stress enough the importance of owning different forms of technical literature.
you got @swathdiver telling everybody who posts a thread to get a TECH2, and there are a couple of threads discussing workshop manuals of both paper & electronic form. I wish they would make that a sticker for every subforum.
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