TPS. Code 21 - Hummer Forums - Enthusiast Forum for Hummer Owners

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Old 11-15-2011, 09:24 PM
Join Date: Mar 2011
Posts: 46
Default TPS. Code 21

I write to you because I am still battling some issues with my H1. A quick reminder: I own a 1995 6.5 NA that was having some tranny issues. I replaced the transmission and some of the symptoms of not shifting smoothly have vanished. As recommended, I ensured the grounding points were tight and the TPS was calibrated with the required block. I am now in a scenario where I get code 21 with the tranny stuck in safe mode. I hooked up the Tech1 with the engine off and watched the TPS voltage and % jump around and never settle down. Also, after applying the throttle it seems to get stuck at 35%. Following the manuals troubleshooting instructions I have checked for voltages and shorts. One of the last parts for troubleshooting code 21 is to jump two pins on the TCM, which I did. The result did not show a voltage greater than 4.9v per the tech manual and is hinting at a bad TCM or a possible short/ground. Have you seen symptoms like that which lead to a bad TCM? Can a TCM be tested at a dealer? Where can I buy one? How much are they? Any suggestions/tips? Part numbers? I do not have any wiring diagrams for the truck except the one for the transmission. Any help would be appreciated. Thank you in advance.

Very Respectfully,
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1995, 21, block, check, code, codes, ground, h1, h2, hummer, location, points, problems, stuck, tcm, tps

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