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Discussion Starter · #1 ·
has anyone had success in marrying the stock Colorado dash to the 5.3 ECM? I'm thinking that I could just connect the serial data wire to the stock dash??? Any constructive comments are welcome.
 

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i would suggest calling “James”. He is one of the most knowledgeable people on this forum.
His number is: 732-690-6443. If anyone is able to answer your question, he is your man.
 

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Discussion Starter · #3 ·
Well, I went ahead and did it and to my surprise it worked. I still have to connect my fuel gauge to the 5.3 PCM, but once I do that all gauges are going to work and I didn't have to spend $800 for a new set.
 

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usually the fuel gauge reads backwards after swap. most just swap the two sending unit wires to get it to read proper. just a heads up. sorry i didn't see this sooner but your correct. serial data wire to connector on pass side of fire wall makes all gauges function and obd2 under dash will work as well.
 

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Discussion Starter · #5 ·
Thanks, I connected the gas gauge and it works, but I don't know yet if it is backwards. Just in case, when people swap the wires do they do it at the tank?
 

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Anywhere between the pump and main harness wouldn't matter. Switched is switched. But yes if it was me I'd do it at the pump since that would be the easiest and cleanest way. If needed you can try pulling driver's rear wheel well liner and might be able to unplug the pump that way and fish the harness out, swap pins then replace.
 

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hi i have an 09 Colorado i recently put in a 02 tahoe 5.3 in it but my gauges dont work i was wondering what wire did you tie in to make yours work?

Thanks Randy
 

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serial data wire of ecu to the blue connector near the passenger fire wall. forget which pin and plug, want to say 15. purple wire
 

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Cool when the guy did me harness he has the tech and bad wire sticking out of the pcm plugs will that that have to be hooked up to that blue plug or it does not matter?
 

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vss goes to transmission. should have been to a plug already o connector if you will. speedo works off the serial data line like described above. serial data to connector at firewall pass. side. that goes to BCM, BCM talks to gauges, etc
 

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I tried to put that vss wire to that blue serial plug but it kills all my other gauges and shuts off my dash cluster lights also. Is there a specific wire I need to tie into just for the Speedo and if so where can I find it and what color is the wire? Thanks Randy
 

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you should probably re-read my post above. VSS goes to TRANSMISSION. your connecting random things to your BCM and possibly have no fried some things. hopefully you go lucky and its all good. the serial data wire of the ecu goes to the data wire within that blue plug, pin 15 purple wire specifically. that is it. once done your tach and speedo should work. if not then you have other issues already within the truck, aka bad speedo, bad speedo wiring, bcm wiring, etc etc.you have to ask, why does everything else works that's on the same harness and data line but the speedo? possible something wrong with the speedo or the bcm signal to the speedo. not sure but you may want to seek a wiring diagrham after you get it actually wired up properly and start diagnosis it.
 

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So I don't hook up that vss wire to anything? Soon as I unplug it my tach and temp gauge works again. How can I tell if it's a bad Speedo or wiring?
 

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bartholomewr1 your not reading my post sir, i clearly stated twice now that the vss goes to transmission, that wire should be within a connector and connects to a speed sensor on the transmission that reads shaft speed. as far as diag on your speedo and wiring. that's basic wiring stuff and if you don't know how to check wiring, then id recommend finding a local professional to help you, i cant diag and go back and forth with you teaching you how to do mechanical work easily sir. also maybe create your own thread instead of clogging up someone else.

Rgorilla sorry for hijacking your thread sir, did you ever verify your fuel gauge is reading properly yet? the backwards reading is common on these swap and just curious if yours was a unicorn and worked out lol
 

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"My vss wire is plug in to the transmission the guy who did my harness said that wire is for an output, It's sticking out from the 02 tahoe pcm."

Just curious. What did "the guy who did my harness" tell you when you asked him about this problem?
 

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So, he gave you no instructions regarding where to connect the end of the wire? If the person(s) that constructed the harness for you cannot provide you with the detailed information that you need, there probably isn't anyone here that will have that info. Unless someone here has personally seen the installation and modifications that you have done, they will only be able to make educated guesses regarding what has to be done to complete that installation.

The speedometer, tachometer, temperature and fuel gauges are all on the Serial Data Bus. If the tachometer and temperature gauges are operating normally, as you said, the Serial Data Bus is connected. That indicates that you do not have a valid signal between the VSS and the ECM, for the speedometer, and between the fuel pump and the ECM, for the fuel gauge.

Did "the guy who did my harness" provide you with a wiring schematic?
 
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