1991 Dodge Shadow No Speedometer or Tach

Tiny
JUSTDON
  • MEMBER
  • 1991 DODGE SHADOW
Computer problem
1991 Dodge Shadow 4 cyl Front Wheel Drive Automatic

The speedometer hasn't worked for some time now. A new distance sensor failed to fix the problem. Now, the Tach has stopped. Over a three day period, it would work iat times and then just stopped.

I subscribed to Eautorepair and looked for a Tachometer test procedure. I followed the instructions:

Battery Voltage to proper cavity
Continuity to ground at Cavity F
Tach signal from computer (sbec) at cavity H was 2 volts. The instructions said to have at least one volt.

Zero Ohm from pin 43 of computer to cavity H = good continuity in signal wire.

With the help of a local salvage yard, I replaced the Tach drive module three times, the tachometer assembly twice, tried another complete cluster assembly with negative results, and tried a computer out of a 91 Dodge Spirit (salvage yard said it was compatable). Still nothing.

The car starts up fine and the small gauges all work.

Please Help!
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Friday, July 4th, 2008 AT 8:00 AM

7 Replies

Tiny
JACK42
  • MEMBER
Have you checked any of the main wiring harness connectors from the engine compartment to the interior harness? Both of those signals originate under the hood. Sounds like you have a handle on testing so be sure the wiring and connections are good from the outside in
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Friday, July 4th, 2008 AT 8:12 AM
Tiny
JUSTDON
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Thank You for such a quick response.

If there is the proper signal wire voltage, what would I be looking for? Do you know where the computer gets the information to send through the Tach signal wire?
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Friday, July 4th, 2008 AT 8:16 AM
Tiny
JACK42
  • MEMBER
Looks like it comes out of the distributor
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Saturday, July 5th, 2008 AT 7:56 AM
Tiny
JUSTDON
  • MEMBER
It seems that the tach. Works off of the dome light fuse #13 I think. It does go to the cluster. The owner had pulled the fuse out due to problems with the dome lights lighting at will. When I plugged the fuse back in, the tach. Started working. I pulled it back out and the tach. Snapped to zero again. I have left the fuse in for the time being. However, it is now reading wrong. At an idle, it sits on zero. It will bump up when the engine speed is increased. Is there some Dodge secret that needs to be done to the tach for it to start reading right again?

Since there is some type of problem with the dome lighting system, could this be causing the tach to display zero at idle?
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Tuesday, July 8th, 2008 AT 11:20 AM
Tiny
JACK42
  • MEMBER
Is this the original cluster or th ereplacement one? if the other car was a 6 cyl it may explain why it wont read at idle. Try going here

http://www.2carpros.com/articles/mitchell1eautorepair-car-repair-manuals

All the wiring diagrams for oyur car are there, There may even be a buffer of some kind in the cluster that is causing this
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Wednesday, July 9th, 2008 AT 7:23 AM
Tiny
JUSTDON
  • MEMBER
It's the original one. I have the diagrams from e-auto repair allready.

I'll keep checking.
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+1
Wednesday, July 9th, 2008 AT 7:52 AM
Tiny
JUSTDON
  • MEMBER
Since I had taken the cluster from the salvage yard apart, I placed the wrong electromagnetic thingy on the tach. I switched that out with the one that was on the original tach and it now reads the proper rpm's.

I don't really understand it but, if it isn't broke.I'm not going to fix it. Lol
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Saturday, July 12th, 2008 AT 12:41 AM

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