89 C1500 LQ9 4L80 Speedomoter

[eg30.06]

Hey all, I'm finishing up a engine swap on my 1989 C1500. Was originally a 4.3 auto, now 6.0 4l80. Everything works but I can't seem to get the speedometer to work and it did function before the swap. Tried splicing the original vss Purple and yellow wires to the vss output of the trans with no luck. Then I tried wiring the 2000 ppm vss from the LS harness to 16A in the cluster, nothing. I've searched through manuals, schematics etc. What am I doing wrong?

 

[Drunkcanuk]

This is crazy....my bud and I were literally just talking about this last night. He swapped a LS into a 65 F100.
I have a 91 I'm contemplating swapping. He said something about LS1tech.com having all the answers needed there.
Hopefully someone here has an answer.
How do you like the 6.0? I would be replacing a 350 so not quite the same. Does it get up and go like hell?

 

[eg30.06]

It goes freaking awesome lol even with 308 gears. Worth every penny so far. Plans for next winter are 373 gears, locker, cam, single turbo, and holley terminator x max. This year finish bodywork and work out bugs.

 

[Schurkey]

'89 should be just like my '88.

The VSS supplies signal directly to the INSTRUMENT CLUSTER. The DRAC in the instrument cluster processes the VSS signal, distributes it to the Speedo, Odometer, Cruise control, RWAL, and the main computer.

In my case, the instrument cluster (probably the DRAC module) failed intermittently. Spent two years on and off dicking with gauges and VSS sensor/wiring before replacing the instrument cluster with one from a Treasure Yard. When the IC quit processing the signal, all of those items died--speedo, odo, cruise, RWAL, the computer turned on the MIL and disabled the torque converter clutch. A few miles--or a few days--later, everything came back to life. Made diagnosis "fun".

 

[eg30.06]

Thankyou for the response. So I'm assuming my cluster needs work because I tested power from the vss purple and yellow wires to the pins behind the cluster and they are good. Maybe reversed or the fact I spliced into the vss for the LQ9 harness I messing things up?

 

[Schurkey]

Reversed wiring seems feasible, as does the added load from the LQ9 harness. What does the VSS drive in the LQ9 harness?

"I" would be tracking down the original vehicle schematic to assure the VSS wires aren't reversed at the cluster. Once I knew they were correct, and if there was still a problem with the cluster, it's a toss-up whether to replace the cluster or remove the splices to the LQ9 harness to see if the existing cluster comes back to life.

 

[eg30.06]

Last night I tried reversing the purple and yellow without success then plugging directly to the vss also without success.

The vss serves all the output info to the PCM for speed, shifting, tcc lockup, etc.

 

[89RCLB]

I've been gathering parts and info for an LS swap for my 89 K1500. I found this article:

90 C1500 LM7/4L60E swap. Speedo question - LS1TECH - Camaro and Firebird Forum Discussion

Conversions & Swaps - 90 C1500 LM7/4L60E swap. Speedo question - I swapped an 04 LM7 (5.3L) and a 2WD 4L60E into my 1990 chevy RCSB C1500. I used the 04 truck harness and just modified what I needed for powers and grounds etc. My question is this: the stock 90 speedo has the same 4K pulses per...

ls1tech.com

This is the gadget referenced in the above post: https://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=1192/mode=prod/prd1192.htm

 

[Donald Mitchell]

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

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