# How To Fix -90 error code **URL:** \ **Category:** GEM Forum\ **Created:** [January 28, 2024, 1:23am UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411 "2024-01-28T01:23:52Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![pchost](https://avatars.discourse-cdn.com/v4/letter/p/e495f1/32.png) [@pchost](https://community.electricforum.com/u/pchost)\ **Post date:** [January 28, 2024, 1:23am UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/1 "2024-01-28T01:23:52Z")
I have seen the list of codes, but i have not seen any fix or how to trace the -90 error code (Terminal one is shorted to ground, input sensor error inspect motor controller). I have a 2000 GEM 4 person that was a basket case and i have brought to life. Car moves and runs, but has this code and i would like to get all codes clear. Any Help on how to fix? I am not sure where to look. ---
**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:** [January 28, 2024, 1:48am UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/2 "2024-01-28T01:48:22Z")
Where did you find that code description? What controller is in the car? ---
**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:** [January 28, 2024, 1:54am UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/3 "2024-01-28T01:54:01Z")
1. Measure voltage on pin 1. 2. Remove wire from pin 1. See if error code changes. ---
**Author:** ![pchost](https://avatars.discourse-cdn.com/v4/letter/p/e495f1/32.png) [@pchost](https://community.electricforum.com/u/pchost)\ **Post date:** [January 28, 2024, 2:15am UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/4 "2024-01-28T02:15:18Z")
I found the description in this forum under complete list of error codes. The Gauge shows the code, but only when the car is moving. It happens in forward or reverse. The controller has a part # 1C3645SH7R353T2. I assume that means its a T2 controller? ---
**Author:** ![AssyRequired](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/assyrequired/32/7621_2.png) [@AssyRequired](https://community.electricforum.com/u/AssyRequired)\ **Post date:** [January 28, 2024, 2:50am UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/5 "2024-01-28T02:50:48Z")
Yeah - That doesn’t sound like the correct description. It is in that old list that was complied many moons ago. I should go back in and fix that. Does this car run? I helped a couple guys a while back on this. It was quite the rabbit hole. The car would run, but the -90 dominated the PID and would over write speed. This was **not** related to Estimated Battery%. It has to do with cars that have been updated from T1 to T2 controllers. The real early cars did not have a wire in P21 on the controller plug. This is related to the Motor Temp Sensor found in later cars. I even found an old tech document related to this issue. Let me scrounge it up… @pchost → Verify that you do not have a wire in p21. (I bet you do not) ![23p connector num](https://canada1.discourse-cdn.com/flex030/uploads/electricforum/original/2X/9/90ff2cf7354052f98fa48d0bd4cfe7713c70fa25.jpeg) ---
**Author:** ![pchost](https://avatars.discourse-cdn.com/v4/letter/p/e495f1/32.png) [@pchost](https://community.electricforum.com/u/pchost)\ **Post date:** [January 28, 2024, 3:02am UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/6 "2024-01-28T03:02:40Z")
The car runs in fwd and reverse. It does start out slow but it tops out at 25mph. There is no wire in p21. I have no wires in the third row of the main plug (p16-p23). ---
**Author:** ![pchost](https://avatars.discourse-cdn.com/v4/letter/p/e495f1/32.png) [@pchost](https://community.electricforum.com/u/pchost)\ **Post date:** [January 28, 2024, 3:03am UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/7 "2024-01-28T03:03:27Z")
What should the voltage be @ pin 1? ---
**Author:** ![AssyRequired](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/assyrequired/32/7621_2.png) [@AssyRequired](https://community.electricforum.com/u/AssyRequired)\ **Post date:** [January 28, 2024, 3:09am UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/8 "2024-01-28T03:09:16Z")
Pin1 has B+ (+72v) on it as soon as you switch your battery pack Main Disconnect Switch to ON. It is the pre-charge wire. You can also view this is active by measuring across POS and NEG cables on top of the controller. When you switch Key ON, Pin 2 should also have B+ (+72v) on it and the controller should boot up. ---
**Author:** ![pchost](https://avatars.discourse-cdn.com/v4/letter/p/e495f1/32.png) [@pchost](https://community.electricforum.com/u/pchost)\ **Post date:** [January 28, 2024, 3:27am UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/9 "2024-01-28T03:27:19Z")
I’ll have to check this tomorrow. Thanks for the help. ---
**Author:** ![AssyRequired](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/assyrequired/32/7621_2.png) [@AssyRequired](https://community.electricforum.com/u/AssyRequired)\ **Post date:** [January 28, 2024, 2:16pm UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/10 "2024-01-28T14:16:11Z")
But this has nothing to do with P1. That error code description is wrong. It is all about p21. I found another reference on how there was some sort of temp sensor in a heat sink the controller was mounted to. This wire went into p21. ---
**Author:** ![Gem\_e2](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/gem_e2/32/1849_2.png) [@Gem\_e2](https://community.electricforum.com/u/Gem_e2)\ **Post date:** [January 28, 2024, 3:50pm UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/11 "2024-01-28T15:50:06Z")
found this on search code 90 > [@Bunch of T2 Controllers](https://community.electricforum.com/t/bunch-of-t2-controllers/14986/6): > > I just swapped out my T1 with a T2 this weekend. Understand they’re a little better at dissipating heat and are generally a better controller. You need 3 parts - 0106-00678 ASSY, WIRE HARNESS - SPLIT HEATSINK JUMPER 0106-00827 ASSY, WIRE - SPLIT HEAT SINK JUMPER 0606-00176 CONNECTOR, T - WIRE The harness will convert you from 8 pins to 12 for the gauge. Split heat sink and T-Wire will take power from pin #2 and run to pin( #23. edit 2026 DB not pin 23 but pin 21) Without it you’ll get err… **Edit, not pin 23 but pin 21** ---
**Author:** ![AssyRequired](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/assyrequired/32/7621_2.png) [@AssyRequired](https://community.electricforum.com/u/AssyRequired)\ **Post date:** [January 28, 2024, 4:04pm UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/12 "2024-01-28T16:04:36Z")
> Split heat sink and T-Wire will take power from pin #2 and run to pin #23. Be careful of this suggestion. I looks like a typo. We should probably go in and fix it before someone else finds it. It basically takes B+ and runs it into the Serial Comms output. I don’t think it would be a very good thing to do. OTOH- If you look at p21, the chart shows T1 do not use it. But controllers T2, T3, and T4 all will be looking for something on that pin. ![Gem Controller pinouts](https://canada1.discourse-cdn.com/flex030/uploads/electricforum/original/2X/c/c979cd7a04c919eded5a61cd296e7ffb9d9adfd6.png) ---
**Author:** ![Gem\_e2](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/gem_e2/32/1849_2.png) [@Gem\_e2](https://community.electricforum.com/u/Gem_e2)\ **Post date:** [January 28, 2024, 4:10pm UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/13 "2024-01-28T16:10:30Z")
hi yes think you have right ---
**Author:** ![Gem\_e2](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/gem_e2/32/1849_2.png) [@Gem\_e2](https://community.electricforum.com/u/Gem_e2)\ **Post date:** [January 28, 2024, 4:15pm UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/14 "2024-01-28T16:15:21Z")
have read the manual now and it says 21… lnstall the female terminal end of the jumper wire to pin location number twenty one (Pin No. 21). Figure 7 maybe i can send it to you ---
**Author:** ![pchost](https://avatars.discourse-cdn.com/v4/letter/p/e495f1/32.png) [@pchost](https://community.electricforum.com/u/pchost)\ **Post date:** [February 1, 2024, 9:54pm UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/15 "2024-02-01T21:54:31Z")
PIN 1 is only showing 74.1 volts with disconnect turned on. PIN 2 is also showing 74.1 volts with key turned on and disconnect on. Positive and negative on top of controller show 72.4 volts. ---
**Author:** ![AssyRequired](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/assyrequired/32/7621_2.png) [@AssyRequired](https://community.electricforum.com/u/AssyRequired)\ **Post date:** [February 1, 2024, 10:15pm UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/16 "2024-02-01T22:15:57Z")
Ok… Great! That is as expected. Perhaps you missed the other part of the discussion on how you also **need a wire going into p21 and jumping over to p2**? (We previously found your harness does not have wire 21). Whoever did your controller swap/upgrade did not finish the job. This is why your PID is showing you a -90 and your car is restricted in power. ---
**Author:** ![pchost](https://avatars.discourse-cdn.com/v4/letter/p/e495f1/32.png) [@pchost](https://community.electricforum.com/u/pchost)\ **Post date:** [February 1, 2024, 10:17pm UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/17 "2024-02-01T22:17:42Z")
I am in the process of ordering the pin 770854-1 and the splice. Then I’ll wire it up and see if that takes care of it. ---
**Author:** ![pchost](https://avatars.discourse-cdn.com/v4/letter/p/e495f1/32.png) [@pchost](https://community.electricforum.com/u/pchost)\ **Post date:** [February 2, 2024, 4:02pm UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/18 "2024-02-02T16:02:11Z")
Would you have the part number for the 23 pin connector going to the controller? Mine looks nasty and I would rather replace/re pin a new connector now rather than when something happens later. ---
**Author:** ![pchost](https://avatars.discourse-cdn.com/v4/letter/p/e495f1/32.png) [@pchost](https://community.electricforum.com/u/pchost)\ **Post date:** [February 2, 2024, 6:55pm UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/19 "2024-02-02T18:55:58Z")
I took the connector apart and removed the pin for the back up alarm (pin 10). I hate that sound anyway. I took that pin and soldered up my own temporary jumper from pin 2 to pin 21. There is now no delay in the pedal response and best of all, no error code 90. Eventually, I’m going to get some new 23 pin connectors and make a small harness extension to relieve the tension on this harness. These wires are tight. Thanks to all that helped, but especially AssyRequired. Appreciate it!!! ---
**Author:** ![AssyRequired](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.electricforum.com/assyrequired/32/7621_2.png) [@AssyRequired](https://community.electricforum.com/u/AssyRequired)\ **Post date:** [February 2, 2024, 7:12pm UTC](https://community.electricforum.com/t/how-to-fix-90-error-code/27411/20 "2024-02-02T19:12:17Z")
Ha! That is a solution I would not have thought of. Nice job. Why is your harness so tight? Is this car lifted? How much? [Next page](https://community.electricforum.com/t/how-to-fix-90-error-code/27411.md?page=2)