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Speedometer problem by Neils88
Started on: 06-26-2014 08:02 PM
Replies: 3 (382 views)
Last post by: Neils88 on 06-27-2014 09:58 PM
Neils88
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Report this Post06-26-2014 08:02 PM Click Here to See the Profile for Neils88Click Here to Email Neils88Send a Private Message to Neils88Edit/Delete MessageReply w/QuoteDirect Link to This Post
Issues with the speedometer connection....

Originally, during the 4.9L swap, I hooked the speedometer using the following circuit:



Of course the speedometer made no movement all. I tried both ECM outputs (B11 & B12), but still nothing. I checked the VSS, and it was giving a good AC signal. I checked the wires from the VSS to the ECM, and it too was good.

Then at some point during the swap, I realized that I was using the stock Isuzu 5 speed, and therefore the circuit was irrelevant So I spliced the C203 wires (purple and yellow) into the VSS wires (B9 & B10), which essentially put it back into the stock configuration while still feeding the signal to the ECM. However, still nothing!

What am I missing? Is there a way to test the speedometer itself? It was working before the swap and it's unlikely that the filter damaged it, but that's about the only thing I can think of right now.

Any thoughts?
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phonedawgz
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Report this Post06-27-2014 10:54 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Swap the VSS input pins on your ECM's connector.

The dash grounds one of the pins. The ECM grounds one of the pins. GM didn't keep it consistent since the VSS leads ran directly to the ECM and the grounding didn't matter.
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Mickey_Moose
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Report this Post06-27-2014 01:58 PM Click Here to See the Profile for Mickey_MooseClick Here to visit Mickey_Moose's HomePageClick Here to Email Mickey_MooseSend a Private Message to Mickey_MooseEdit/Delete MessageReply w/QuoteDirect Link to This Post
1) you don't need the circuit at all as you can run it directly (with either standard tranny) - HOWEVER - if you change tires sizes and have Stickpony modify the code for those tires sizes, the ECM will output the correct signal so that your speedo will read the correct speed based on your tire size.

2) 4.9 ECM grounds pin 9 internally - the wire that connects ECM pin 10 should also connect to the speedo input (should be the yellow wire in the C203 plug) - do you have a scanner? With the scanner hooked up you should be able to read the speed that the ECM see's.

I assume the speedo was working before (when it was removed for the tach mod - maybe you forgot to plug it back in)? The speedo plug is on the bottom left of the gauge cluster when viewing from the front - the other gauges use the back 2 plugs.

Yes, it is possible to test the speedo - you just need to input a pulse signal. Simplest form is one of those AC wall transformer that outputs a 12V AC signal - cut the plug end off and attach to the speedo input, plug it in a you are good. I don't recall at the moment what speed it will read though (been several years since I did this).
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Neils88
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Report this Post06-27-2014 09:58 PM Click Here to See the Profile for Neils88Click Here to Email Neils88Send a Private Message to Neils88Edit/Delete MessageReply w/QuoteDirect Link to This Post
Thanks! Swapped B9 and B10 and the speedo now works.

I will have to modify when I eventually change the tire size, but for now the speedo works.
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