2003 Hummer H2 speed gauge acting up...

[MasterCodein]

Hi guys,

I rebuilt that cluster and for some reason the speed stepper motor acting up... It was working and now stop... I replace it 3 time it's like it randomly and also sometime it going to the opposite direction... What should check?

Thank youhttps://uploads.tapatalk-cdn.com/20190903/c71c33e90b48dfc88b6ed50f3f341b06.jpg

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[clusters]

Check your soldering and that you did not rip any pads off the back (common with too much heat), the speedo stepper is the hardest to repair because there is no close test points. You would have to run jumper wires.

Going the opposite direction is a dead giveaway that one connection is bad or a broken pad/trace.

[MasterCodein]

All soldering point at the back are ok, I test it many time before putting the cover and then it stop working... What are the soldering areas I should check? The one on the top of the stepper motor?

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[Killer76]

Here is a Silverado core I had laying around. So I marked the jumper points on it for you. Not 100% it's the same as your hummer but they look the same in your photo.

[clusters]

Check right beside the stepper motor pads, look for a broken trace. Unless the problem was present before the rebuild, in which case it could be a bad via (hole through the circuit board). U27 is the stepper motor controller chip for the speedo and others.

Also check for corrosion on the back of the board (grey spots).

Post a picture of the back.

What do you desolder with? Braid is safe if the proper iron temp is used, same for a proper desoldering iron with vacuum. A crappy iron with a solder sucker kills these boards easily.

[MasterCodein]

I think it was present before the rebuilt... But when I first change the stepper motor it work numerous time as I was testing it... Then start acting up... Here is the back of the board https://uploads.tapatalk-cdn.com/20190904/3f35972cef244df472c15ecd6b8e172c.jpg

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[MasterCodein]

Yes lot of corrosion should I use alcohol? Look...https://uploads.tapatalk-cdn.com/20190904/e423d7ddde7c3792cbdb39f7f603c7d7.jpg

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[clusters]

Hard to tell from that, but the soldering looks good and I don't see any damage. Follow the traces and check for continuity to the nearest test point.

If that is all good, then you will have to follow it to the vias and test them as well. Then work back to the controller IC.

There is no silver bullet fix here, it's all tracing and testing.

The corrosion could be causing it, I use alcohol and a pencil eraser to remove it. First step I do when rebuilding these, and I have done hundreds of them. ;)

[MasterCodein]

It work good the sucker never break a trace yet it would of been the first time... Solder braid is too longhttps://uploads.tapatalk-cdn.com/20190904/2a97eccfe926d462a6dd3bb76338be90.jpg

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[MasterCodein]

Ok will try fee stuff and will update.

Thank you

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[MasterCodein]

One more details what is the vias?

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[clusters]

Vias are the small holes that connect the traces from the back of the board to the front. In some cases they can corrode through and lose the connection, I have seen it in a few cases.

To repair it you clean the solder mask off both sides and just solder a strand of wire on both sides.

647832

[MasterCodein]

I was able to do continuity from the stepper motor point to each ria, then from each side of the ria and also from the front ria to U27 and from the stepper motor pin to U27 continuity is working.https://uploads.tapatalk-cdn.com/20190904/84d963f63129cc60a595c09917f94b87.jpg

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[clusters]

Clean the corrosion and I'll bet it solves your problem. ;)

[MasterCodein]

Should I resolder the U27? I didn't do that one, about the corrosion I did remove with alcohol but don't have an eraser yet

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[clusters]

I doubt it is a solder problem, I have never seen it.

Alcohol alone will not clean the corrosion, look at it under magnification.

The vias are usually surrounded by the ground plane, and any corrosion will short that circuit to ground.

[MasterCodein]

Ok

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[MasterCodein]

Still the same... Should I redo the rias even if I have continuity? Doesn't have any resistor in the path to the stepper motor processor?https://uploads.tapatalk-cdn.com/20190904/7a82f5d42179c4c45980d6652377d430.jpghttps://uploads.tapatalk-cdn.com/20190904/ae55809fc07e3d5ee1fdde98c4569f2b.jpghttps://uploads.tapatalk-cdn.com/20190904/0b761db274ea57af5fe9b4d30006a0ba.jpg

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[clusters]

No, there is no resistor in the circuit from the stepper to the IC.

Can't help you any further I guess. Except maybe remove the stepper motor and recheck continuity. One of the traces could be backfeeding through the motor giving you continuity where there is none.

Good luck.

[MasterCodein]

Culprit is pin 4... I will remove all solder and see if it's really break and I will bridge that one.

Thank you DK

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