Hi,
In this post, I'm going to share with you on how to check or test the speedometer component on a 940. I am doing this test based on a 1991 V940 with B230E engine, the wires may have different colors for later models, but principally, it is still the same concept.
Briefly, our cars are equipped with a speedo sensor mounted on the rear axle. This is such a tough component that hardly fails in many instances. This sensor is actuated based on the rear axle speed, which then transmit the signal in sinusoidal form through a wiring harness to the instrument cluster board. It have only a pair of wires (2 wires) laid from the sensor itself to the instrument cluster at the dashboard. This wires often get brittle/cracked/disconnected usually at the axle itself due to exposure to various road conditions (after 20 years of rain, hot, water splashes, etc). This is worth checking first before further checks to be done.
In many cases, we are not sure either the sensor itself worn out or the board? To confirm, do this;
a) First, a continuity test must be done. Detach your car battery first. Then, you may connect both wires at the sensor and using a multimeter, you may check the continuity between these two leads at the instrument board socket. They should indicate high impedance (connected). Then you know either the wires are okay or not.
b) If the wires are okay, but your needle still jumping here and there or do not move at all; re-attach and secure the wires at sensor properly. At the board socket, use a multimeter lead to read from the 2 wires. For this car it is Green/White & Brown/White wires. Put your multimeter in ACV-Mode. Start your car and have a short drive. Observe the multimeter reading. If the multimeter reading increases with your speed, it shows nothing is wrong with your sensor and wires. The board is the culprit. If otherwise, it is worth to recheck the wires before you make a huge investment to change the sensor.
Remember, with the instrument cluster detached, your alternator is not charging the battery! So please have a short test drive only to avoid draining out the battery. You may refer to this page for instrument cluster removal guide, it is very easy for 940 than the 240s! And if it is confirmed that the board is the culprit, this is worth reading!
In this post, I'm going to share with you on how to check or test the speedometer component on a 940. I am doing this test based on a 1991 V940 with B230E engine, the wires may have different colors for later models, but principally, it is still the same concept.
Briefly, our cars are equipped with a speedo sensor mounted on the rear axle. This is such a tough component that hardly fails in many instances. This sensor is actuated based on the rear axle speed, which then transmit the signal in sinusoidal form through a wiring harness to the instrument cluster board. It have only a pair of wires (2 wires) laid from the sensor itself to the instrument cluster at the dashboard. This wires often get brittle/cracked/disconnected usually at the axle itself due to exposure to various road conditions (after 20 years of rain, hot, water splashes, etc). This is worth checking first before further checks to be done.
In many cases, we are not sure either the sensor itself worn out or the board? To confirm, do this;
a) First, a continuity test must be done. Detach your car battery first. Then, you may connect both wires at the sensor and using a multimeter, you may check the continuity between these two leads at the instrument board socket. They should indicate high impedance (connected). Then you know either the wires are okay or not.
b) If the wires are okay, but your needle still jumping here and there or do not move at all; re-attach and secure the wires at sensor properly. At the board socket, use a multimeter lead to read from the 2 wires. For this car it is Green/White & Brown/White wires. Put your multimeter in ACV-Mode. Start your car and have a short drive. Observe the multimeter reading. If the multimeter reading increases with your speed, it shows nothing is wrong with your sensor and wires. The board is the culprit. If otherwise, it is worth to recheck the wires before you make a huge investment to change the sensor.
Remember, with the instrument cluster detached, your alternator is not charging the battery! So please have a short test drive only to avoid draining out the battery. You may refer to this page for instrument cluster removal guide, it is very easy for 940 than the 240s! And if it is confirmed that the board is the culprit, this is worth reading!
4 comments:
THANK YOU- VERY SIMPLE AND CONSCISE
My pleasure... Thanks for the visit :)
This is very helpful and your information is accurate. Ahmad your post is self explanatory and I am going to try it on my volvo that the speedometer has gone bad.
Ahmad how much do you know about Volvo 940.
Can you give me more information on how to check or repair the speedometer.
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