# Temp and rpm gauge

**URL:** <https://boards.straightdope.com/t/temp-and-rpm-gauge/767591>\
**Category:** In My Humble Opinion\
**Created:** [October 3, 2016, 8:34pm UTC](https://boards.straightdope.com/t/temp-and-rpm-gauge/767591 "2016-10-03T20:34:05Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![dwaymich](https://avatars.discourse-cdn.com/v4/letter/d/c4cdca/32.png) [@dwaymich](https://boards.straightdope.com/u/dwaymich)\
**Post date:** [October 3, 2016, 8:34pm UTC](https://boards.straightdope.com/t/temp-and-rpm-gauge/767591/1 "2016-10-03T20:34:05Z")

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I have a 1994 Mazda 626, 2.0. I used the 10 pin and negative pin to set my idle. Now my rpm and temperature gauge doesn’t work. They are not digital. I did see a small spark when I put the jumper pin in my diagnostic box. I check the fuses but I’m not for sure if I might have overlooked something. I reset my computer but still nothing. Does anyone have some good advice for me. Thank

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**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\
**Post date:** [October 3, 2016, 9:02pm UTC](https://boards.straightdope.com/t/temp-and-rpm-gauge/767591/2 "2016-10-03T21:02:07Z")

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Since the OP is looking for advice, let’s move this to IMHO.

Colibri  
General Questions Moderator

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**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\
**Post date:** [October 3, 2016, 11:02pm UTC](https://boards.straightdope.com/t/temp-and-rpm-gauge/767591/3 "2016-10-03T23:02:12Z")

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Almost certainly the jumper wire touched the wrong terminal and blew a fuse. This would explain the spark and loss of gauge operation. The terminal next to TEN is a switched power feed that also supplies the gauges through fuse #8. Replace it, being sure to use a 15 amp fuse.

The reliable way to test a fuse is with a test light or voltmeter, with the circuit energized. While visual inspection will often reveal a faulty fuse, it’s possible for a fuse to look okay but not work.

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**Author:** ![Me\_Billy](https://avatars.discourse-cdn.com/v4/letter/m/e480ec/32.png) [@Me\_Billy](https://boards.straightdope.com/u/Me_Billy)\
**Post date:** [October 4, 2016, 3:08pm UTC](https://boards.straightdope.com/t/temp-and-rpm-gauge/767591/4 "2016-10-04T15:08:58Z")

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My advice: Don’t put jumper wires in your diagnostic socket. Take the car to a mechanic. (And DO tell him what you did.)