diff --git a/board/drivers/gmlan_alt.h b/board/drivers/gmlan_alt.h
index 45378747d..1c20e1ed7 100644
--- a/board/drivers/gmlan_alt.h
+++ b/board/drivers/gmlan_alt.h
@@ -121,23 +121,23 @@ int get_bit_message(char *out, CANPacket_t *to_bang) {
   return len;
 }
 
-void TIM12_IRQ_Handler(void);
+void GMLAN_BITBANG_IRQ_Handler(void);
 
 void setup_timer(void) {
   // register interrupt
-  REGISTER_INTERRUPT(TIM8_BRK_TIM12_IRQn, TIM12_IRQ_Handler, 40000U, FAULT_INTERRUPT_RATE_GMLAN)
+  REGISTER_INTERRUPT(GMLAN_BITBANG_TIMER_IRQ, GMLAN_BITBANG_IRQ_Handler, 40000U, FAULT_INTERRUPT_RATE_GMLAN)
 
   // setup
-  register_set(&(TIM12->PSC), (APB1_TIMER_FREQ-1U), 0xFFFFU);    // Tick on 1 us
-  register_set(&(TIM12->CR1), TIM_CR1_CEN, 0x3FU); // Enable
-  register_set(&(TIM12->ARR), (30U-1U), 0xFFFFU);   // 33.3 kbps
+  register_set(&(GMLAN_BITBANG_TIMER->PSC), (APB1_TIMER_FREQ-1U), 0xFFFFU);    // Tick on 1 us
+  register_set(&(GMLAN_BITBANG_TIMER->CR1), TIM_CR1_CEN, 0x3FU); // Enable
+  register_set(&(GMLAN_BITBANG_TIMER->ARR), (30U-1U), 0xFFFFU);   // 33.3 kbps
 
   // in case it's disabled
-  NVIC_EnableIRQ(TIM8_BRK_TIM12_IRQn);
+  NVIC_EnableIRQ(GMLAN_BITBANG_TIMER_IRQ);
 
   // run the interrupt
-  register_set(&(TIM12->DIER), TIM_DIER_UIE, 0x5F5FU); // Update interrupt
-  TIM12->SR = 0;
+  register_set(&(GMLAN_BITBANG_TIMER->DIER), TIM_DIER_UIE, 0x5F5FU); // Update interrupt
+  GMLAN_BITBANG_TIMER->SR = 0;
 }
 
 int gmlan_timeout_counter = GMLAN_TICKS_PER_TIMEOUT_TICKLE; //GMLAN transceiver times out every 17ms held high; tickle every 15ms
@@ -191,9 +191,9 @@ int gmlan_fail_count = 0;
 #define REQUIRED_SILENT_TIME 10
 #define MAX_FAIL_COUNT 10
 
-void TIM12_IRQ_Handler(void) {
+void GMLAN_BITBANG_IRQ_Handler(void) {
   if (gmlan_alt_mode == BITBANG) {
-    if ((TIM12->SR & TIM_SR_UIF) && (gmlan_sendmax != -1)) {
+    if ((GMLAN_BITBANG_TIMER->SR & TIM_SR_UIF) && (gmlan_sendmax != -1)) {
       int read = get_gpio_input(GPIOB, 12);
       if (gmlan_silent_count < REQUIRED_SILENT_TIME) {
         if (read == 0) {
@@ -235,13 +235,13 @@ void TIM12_IRQ_Handler(void) {
       if ((gmlan_sending == gmlan_sendmax) || (gmlan_fail_count == MAX_FAIL_COUNT)) {
         set_bitbanged_gmlan(1); // recessive
         set_gpio_mode(GPIOB, 13, MODE_INPUT);
-        register_clear_bits(&(TIM12->DIER), TIM_DIER_UIE); // No update interrupt
-        register_set(&(TIM12->CR1), 0U, 0x3FU); // Disable timer
+        register_clear_bits(&(GMLAN_BITBANG_TIMER->DIER), TIM_DIER_UIE); // No update interrupt
+        register_set(&(GMLAN_BITBANG_TIMER->CR1), 0U, 0x3FU); // Disable timer
         gmlan_sendmax = -1;   // exit
       }
     }
   } else if (gmlan_alt_mode == GPIO_SWITCH) {
-    if ((TIM12->SR & TIM_SR_UIF) && (gmlan_switch_below_timeout != -1)) {
+    if ((GMLAN_BITBANG_TIMER->SR & TIM_SR_UIF) && (gmlan_switch_below_timeout != -1)) {
       if ((can_timeout_counter == 0) && gmlan_switch_timeout_enable) {
         //it has been more than 1 second since timeout was reset; disable timer and restore the GMLAN output
         set_gpio_output(GPIOB, 13, GMLAN_LOW);
@@ -265,14 +265,13 @@ void TIM12_IRQ_Handler(void) {
   } else {
     // Invalid GMLAN mode. Do not put a print statement here, way too fast to keep up with
   }
-  TIM12->SR = 0;
+  GMLAN_BITBANG_TIMER->SR = 0;
 }
 
 bool bitbang_gmlan(CANPacket_t *to_bang) {
   gmlan_send_ok = true;
   gmlan_alt_mode = BITBANG;
 
-#ifndef STM32H7
   if (gmlan_sendmax == -1) {
     int len = get_bit_message(pkt_stuffed, to_bang);
     gmlan_fail_count = 0;
@@ -286,8 +285,5 @@ bool bitbang_gmlan(CANPacket_t *to_bang) {
     // 33kbps
     setup_timer();
   }
-#else
-  UNUSED(to_bang);
-#endif
   return gmlan_send_ok;
 }
diff --git a/board/stm32fx/stm32fx_config.h b/board/stm32fx/stm32fx_config.h
index b47011921..4d382e0e7 100644
--- a/board/stm32fx/stm32fx_config.h
+++ b/board/stm32fx/stm32fx_config.h
@@ -28,6 +28,9 @@
 #define TICK_TIMER_IRQ TIM1_BRK_TIM9_IRQn
 #define TICK_TIMER TIM9
 
+#define GMLAN_BITBANG_TIMER_IRQ TIM8_BRK_TIM12_IRQn
+#define GMLAN_BITBANG_TIMER TIM12
+
 #define MICROSECOND_TIMER TIM2
 
 #define INTERRUPT_TIMER_IRQ TIM6_DAC_IRQn
diff --git a/board/stm32h7/peripherals.h b/board/stm32h7/peripherals.h
index b60f19016..db8c0221e 100644
--- a/board/stm32h7/peripherals.h
+++ b/board/stm32h7/peripherals.h
@@ -124,8 +124,8 @@ void peripherals_init(void) {
   RCC->APB1LENR |= RCC_APB1LENR_TIM3EN;  // fan pwm
   RCC->APB1LENR |= RCC_APB1LENR_TIM6EN;  // interrupt timer
   RCC->APB1LENR |= RCC_APB1LENR_TIM7EN;  // DMA trigger timer
-  RCC->APB2ENR |= RCC_APB2ENR_TIM8EN;  // tick timer
-  RCC->APB1LENR |= RCC_APB1LENR_TIM12EN;  // slow loop
+  RCC->APB1LENR |= RCC_APB1LENR_TIM12EN;  // tick timer
+  RCC->APB1LENR |= RCC_APB1LENR_TIM13EN;  // gmlan bitbang timer
 
 #ifdef PANDA_JUNGLE
   RCC->AHB3ENR |= RCC_AHB3ENR_SDMMC1EN; // SDMMC
diff --git a/board/stm32h7/stm32h7_config.h b/board/stm32h7/stm32h7_config.h
index a7d54274b..880ee4559 100644
--- a/board/stm32h7/stm32h7_config.h
+++ b/board/stm32h7/stm32h7_config.h
@@ -36,6 +36,9 @@ separate IRQs for RX and TX.
 #define TICK_TIMER_IRQ TIM8_BRK_TIM12_IRQn
 #define TICK_TIMER TIM12
 
+#define GMLAN_BITBANG_TIMER_IRQ TIM8_UP_TIM13_IRQn
+#define GMLAN_BITBANG_TIMER TIM13
+
 #define MICROSECOND_TIMER TIM2
 
 #define INTERRUPT_TIMER_IRQ TIM6_DAC_IRQn
diff --git a/tests/hitl/3_usb_to_can.py b/tests/hitl/3_usb_to_can.py
index 9321eb4e8..401a81bfa 100644
--- a/tests/hitl/3_usb_to_can.py
+++ b/tests/hitl/3_usb_to_can.py
@@ -119,6 +119,14 @@ def test_gmlan_bad_toggle(p):
     assert comp_kbps_normal > (0.6 * SPEED_NORMAL)
     assert comp_kbps_normal < (1.0 * SPEED_NORMAL)
 
+@pytest.mark.panda_expect_can_error
+@pytest.mark.skip_panda_types(PandaGroup.GMLAN)
+def test_gmlan_bitbang(p):
+  p.set_safety_mode(Panda.SAFETY_ALLOUTPUT)
+  for _ in range(10):
+    p.can_send(0x10, b"data", 3)
+    time.sleep(0.1)
+  assert p.health()['gmlan_send_errs'] == 0
 
 # this will fail if you have hardware serial connected
 def test_serial_debug(p):