# Speed Sensor Rebuild **URL:** \ **Category:** GEM Forum\ **Created:** [October 2, 2018, 1:53pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639 "2018-10-02T13:53:32Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![timholmesjr](https://avatars.discourse-cdn.com/v4/letter/t/e274bd/32.png) [@timholmesjr](https://community.electricforum.com/u/timholmesjr)\ **Post date:** [October 2, 2018, 1:53pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/1 "2018-10-02T13:53:32Z")
I have read about people sending their speed sensors for evaluation / repair. Anybody know the company info? ---
**Author:** ![Derrick](https://avatars.discourse-cdn.com/v4/letter/d/d9b06d/32.png) [@Derrick](https://community.electricforum.com/u/Derrick)\ **Post date:** [October 2, 2018, 2:13pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/2 "2018-10-02T14:13:56Z")
Look online at amazon and eBay, they are quite cheap if you’re not looking for a brand name one. I think I paid $7-15 for mine. ---
**Author:** ![Inwo](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/inwo/32/1067_2.png) [@Inwo](https://community.electricforum.com/u/Inwo)\ **Post date:** [October 2, 2018, 2:18pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/3 "2018-10-02T14:18:56Z")
Easy to test yourself. Connect an analog meter to blk and green, Roll car. Volts will read \>3.5v and pull down near zero at each magnet pole. Number of pulses in 1/4 turn equals gear ratio. Go a full turn and divide by 4 for more accuracy. ---
**Author:** ![timholmesjr](https://avatars.discourse-cdn.com/v4/letter/t/e274bd/32.png) [@timholmesjr](https://community.electricforum.com/u/timholmesjr)\ **Post date:** [October 2, 2018, 2:21pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/4 "2018-10-02T14:21:47Z")
Thanks. I am seeing anywhere from 4.0-0.00 but it seems erratic. That may be due to the gear ratio I am trying to trouble shoot a situation where at a full charge, my 2006 GEM will operate normally for about 10 min. After 10 min it slows to a crawl. I have tested the batteries. I have had the accelerator assembly rebuilt. My last thoughts were speed sensor or controller. ---
**Author:** ![timholmesjr](https://avatars.discourse-cdn.com/v4/letter/t/e274bd/32.png) [@timholmesjr](https://community.electricforum.com/u/timholmesjr)\ **Post date:** [October 2, 2018, 2:22pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/5 "2018-10-02T14:22:50Z")
I should note that I am getting what feels to be an accurate speedometer reading. That prob should eliminate the speed sensor. I am somewhat grasping at straws. ---
**Author:** ![Inwo](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/inwo/32/1067_2.png) [@Inwo](https://community.electricforum.com/u/Inwo)\ **Post date:** [October 2, 2018, 3:23pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/6 "2018-10-02T15:23:44Z")
I would suspect batteries or connections. Connect leads from controller B- to pin #1 where voltage is sensed, then from B- to B+. A single dip in voltage will put it in turtle mode. ---
**Author:** ![timholmesjr](https://avatars.discourse-cdn.com/v4/letter/t/e274bd/32.png) [@timholmesjr](https://community.electricforum.com/u/timholmesjr)\ **Post date:** [October 2, 2018, 5:57pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/7 "2018-10-02T17:57:14Z")
Would it kick up an error code in that situation? The dash appears fine. I, too, thought it was the batteries. They are one year old. I took them to the dealership and the load tested them individually. Everything checked out. ---
**Author:** ![Old\_Houseboater](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/old_houseboater/32/544_2.png) [@Old\_Houseboater](https://community.electricforum.com/u/Old_Houseboater)\ **Post date:** [October 2, 2018, 6:09pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/8 "2018-10-02T18:09:49Z")
What type and size of batteries? 1 bad cell can cause your symptoms. Symptoms are typical for battery with a a bad cell. Do a brake load test on each battery. ---
**Author:** ![Inwo](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/inwo/32/1067_2.png) [@Inwo](https://community.electricforum.com/u/Inwo)\ **Post date:** [October 2, 2018, 6:28pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/9 "2018-10-02T18:28:48Z")
> [@timholmesjr](#): > > Would it kick up an error code in that situation? The dash appears fine. I, too, thought it was the batteries. They are one year old. I took them to the dealership and the load tested them individually. Everything checked out. Yes, it would show turtle mode. Don’t know what to tell you. ☹ ---
**Author:** ![timholmesjr](https://avatars.discourse-cdn.com/v4/letter/t/e274bd/32.png) [@timholmesjr](https://community.electricforum.com/u/timholmesjr)\ **Post date:** [October 2, 2018, 6:47pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/10 "2018-10-02T18:47:19Z")
Can you give me the step by step on the brake load test. I gather you are wanting to create a high amp draw situation. Are you measuring the voltage of each battery during the test? The batteries are Deka Group 31 marine deep cycle lead acid. ---
**Author:** ![Inwo](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/inwo/32/1067_2.png) [@Inwo](https://community.electricforum.com/u/Inwo)\ **Post date:** [October 2, 2018, 8:50pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/11 "2018-10-02T20:50:34Z")
Yes, he means butt it up against a block, safely, and measure each battery under load. As much throttle as is safe. Might also be helpful to test the whole string right at the controller. ---
**Author:** ![Old\_Houseboater](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/old_houseboater/32/544_2.png) [@Old\_Houseboater](https://community.electricforum.com/u/Old_Houseboater)\ **Post date:** [October 2, 2018, 9:39pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/12 "2018-10-02T21:39:56Z")
Attach your voltmeter to a battery - hold your foot hard on the brake - push the accelerator pedal down for 3 to 4 seconds and note the voltage.- repeat on each battery. The dog will show up. Let us know your results. Rodney In a message dated 10/2/2018 2:57:21 PM US Eastern Standard Time, [electricforum@discoursemail.com](mailto:electricforum@discoursemail.com) writes: ![](https://canada1.discourse-cdn.com/flex030/uploads/electricforum/original/2X/6/6f2192bfabd817ccf6e38052e8d9eb06a496d9d9.png "timholmesjr") [timholmesjr](https://community.electricforum.com/u/timholmesjr) Junior Member October 2 Can you give me the step by step on the brake load test. I gather you are wanting to create a high amp draw situation. Are you measuring the voltage of each battery during the test? The batteries are Deka Group 31 marine deep cycle lead acid. ---
**Author:** ![timholmesjr](https://avatars.discourse-cdn.com/v4/letter/t/e274bd/32.png) [@timholmesjr](https://community.electricforum.com/u/timholmesjr)\ **Post date:** [October 2, 2018, 10:05pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/13 "2018-10-02T22:05:47Z")
I performed the load test with no conclusive results. On the first battery voltage dropped by about .5 volts. As I progressed through the other 5 batteries the voltage drop was less and less. By the 6th battery it was non existent. But, by the 6th battery the car would not move. at all. I rechecked the first battery, it performed just like the 6th. In summary, I think that they all are performing similarly. The contactor continued to engage and disengage with each test. Any chance the controller began “demanding” less and less power? Any idea what to test yet? Individual battery voltage has dropped to about 12.1. I will put it on the charger tonight. I can retest tomorrow at at full SOC, but I am not sure I will get diff results ---
**Author:** ![Inwo](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/inwo/32/1067_2.png) [@Inwo](https://community.electricforum.com/u/Inwo)\ **Post date:** [October 2, 2018, 11:16pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/14 "2018-10-02T23:16:52Z")
Do the test right at the controller. If little drop, you are correct. The motor/controller are demanding less current. Something should get hot during the test. Feel the connections at controller and at each battery connection. If you had Sentry monitor sw, you could monitor current and voltage under load. ---
**Author:** ![timholmesjr](https://avatars.discourse-cdn.com/v4/letter/t/e274bd/32.png) [@timholmesjr](https://community.electricforum.com/u/timholmesjr)\ **Post date:** [October 4, 2018, 4:23pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/15 "2018-10-04T16:23:00Z")
Are Sentry monitors still sold or rented? I will try and test the car again today. ---
**Author:** ![timholmesjr](https://avatars.discourse-cdn.com/v4/letter/t/e274bd/32.png) [@timholmesjr](https://community.electricforum.com/u/timholmesjr)\ **Post date:** [October 4, 2018, 9:45pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/16 "2018-10-04T21:45:45Z")
Latest update… I tried testing at the controller. At full throttle and standing on the brake the voltage dropped from 74 to about 71.5. This was repeated about 5 times. I then left the key on and let the unit sit there for 10 min. After the time had elapsed I retested and there was no voltage drop and no movement by the car. Nothing felt hot that I could tell. At least the battery connections both in series and connected to the controller were not hot. My next test is turning the car on and letting it sit for 10 min then try the voltage test and see if it will move. Does this begin to look like a controller? If so, is FSIP the best resource as they can bench test it? ---
**Author:** ![Old\_Houseboater](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/old_houseboater/32/544_2.png) [@Old\_Houseboater](https://community.electricforum.com/u/Old_Houseboater)\ **Post date:** [October 4, 2018, 10:46pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/17 "2018-10-04T22:46:33Z")
Really need to test each battery individually, What year is cart. Classic symptom for bad throttle control on 2005 and up. Rodney ---
**Author:** ![Inwo](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/inwo/32/1067_2.png) [@Inwo](https://community.electricforum.com/u/Inwo)\ **Post date:** [October 4, 2018, 11:13pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/18 "2018-10-04T23:13:37Z")
Pin 7 is from the throttle. 0-4vdc. ---
**Author:** ![Inwo](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/inwo/32/1067_2.png) [@Inwo](https://community.electricforum.com/u/Inwo)\ **Post date:** [October 4, 2018, 11:14pm UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/19 "2018-10-04T23:14:24Z")
> [@timholmesjr](#): > > Are Sentry monitors still sold or rented? I will try and test the car again today. I can set you up. What controller do you have? ---
**Author:** ![timholmesjr](https://avatars.discourse-cdn.com/v4/letter/t/e274bd/32.png) [@timholmesjr](https://community.electricforum.com/u/timholmesjr)\ **Post date:** [October 5, 2018, 12:15am UTC](https://community.electricforum.com/t/speed-sensor-rebuild/14639/20 "2018-10-05T00:15:29Z")
I have individually charged the batteries and taken them to the distributor for load testing. I also had the accelerator assembly reworked by FSIP (I think they just cleaned to contacts, but supposedly bench tested it to verify) [Next page](https://community.electricforum.com/t/speed-sensor-rebuild/14639.md?page=2)