QuestionSo. The answer was very helpful. However I have a few questions:
When you say the red plug you are referring to the one on the back of the dash panel/speedometer panel correct? How do I tell which pin is pin C?
How do I tell weather I have a electronic or mechanic cluster? Or am I misunderstanding this? This is where I got a little confused.
Also if I find that the signal is not getting transmitted from the speed sensor to the ECM can I bypass everything and run a wire right from the speed sensor to pin 47 or is there other things involved?
Finally is there anything/where specific that you can think of to check first to possibly save time?
Thanks a BUNCH! Very helpful!
-TOM
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The text above is a follow-up to ...
-----Question-----
I have a 91 dodge dynasty 3.3l manual and the speedometer/odometer is not working. I've replaced the speed sensor and also the dash unit in hopes to fix this to no luck! The old "nasty" as I call it is pretty rusty but runs good and I'm thinking it's something electrical.
How do I test to see if it's getting readings to/from the speed sensor? I know this is a common prob with these little devils and tried to find the answer but couldn't! Thanks for your help in advance! -TOM
-----Answer-----
Hi Tom,
If you disconnect the plug at the sensor and put an ohmmeter across the terminals, then lift the right front wheel so you can rotate it, then watch the ohmmeter to pulse 8 times for each rotation of the wheel, that will be its test. The wires from the plug are:
white/orange goes to pin 47 of the 60-way at the engine controller, and black/light blue is a common ground for many sensors that goes to pin 4 of the same plug.
The signal for the cluster is different for the mechanical and electronic units. The mechanical uses a splice off the white/orange wire that goes directly to pin C of the red plug (check for continuity from C to the sensor), whereas the electronic cluster takes a digital data bus signal from the controller that combines the speed/distance sensor data with many others and sends it on a single pair of twisted wires so that the speedo alone will not fail unless all the other data to the cluster also fails, or the cluster itself fails in the speedo section. So depending on your cluster type, trace accordingly.
I hope this is clarifying.
Roland
AnswerHi Tom,
Thank you for the very generous evaluation.
On the red plug, yes I am referring to the cluster. On the conventional (mechanical cluster) the displays are analog meters, on the electronic cluster the displays are digital or bar graphs. Both have red plugs, but the shape is round on the conventional and rectangular on the electronic.
You will find the pin ID's engraved next to the pin, or you can simply look for the location of the specific colored wire to find its pin.
Yes, you can run a wire directly, but it would be worth finding out where the break is and repairing it because the wires are better protected if in a harness with other wires. There is one splice for example which is where a break could have occured, and one 10-pin disconnect plug where a break could occur, or a poor connection at the plugs on either end of the wire from the sensor to the cluster and/or ecm. But cross that bridge when you get to it.
I would start at the sensor's plug and check the sensor for pulsing, and then check the white/orange from the other side of that plug to the ecm (and if you have the mechanical cluster to the red plug also).
Roland
