JWingo

Going home yesterday and here we go! Service ABS, Service Active Handling, Service traction control. The c1237 would say to much system voltage. Alternator is @ 14.2 vdc and the battery voltage is @ 13.6 vdc. The alternator is around one week old. I have checked grounds and did voltage drop test. I'm wondering if this could just be the EBCM getting ready to leave here. Anyone have the same issue?

trussme

the voltage regulator in the alternator may be stuck open. It can also overcharge and ruin your battery if you do not correct the problem.
Check the voltage across the battery terminals or at the alternator and see if you are getting over 15 volts there.

Did you have the problem before you replaced the alternator?

Measure the charging voltage, at the battery, with an accurate digital voltmeter.

Determine if the measured voltage is the same or not, as the displayed voltage on the instrument cluster.

If the voltage measured at the battery is normal, the alternator regulator
is not the problem.

JWingo

Voltage at the alternator is 14 to 14.4 vdc. Voltage at the battery is around 13.8. The first alternator made my headlights get bright and then dim. The new one solved that.

trussme

is it a History or Current code...tried resetting/erasing this code to see if it returns?

trussme

When that code is set it means the EBCM detected a voltage above 17 volts for a short period of time. If the voltage level is too high (above 17 volts), damage may result in the system. When the EBCM detects a high voltage condition, the EBCM turns OFF the system relay which removes battery voltage from the solenoid valves and pump motor.

Here is the diagnostic procedure for that code:
DTC C1237


Circuit Description

The electronic brake control module (EBCM) monitors the voltage level available for system operation. If the voltage level is too high, damage may result in the system. When the EBCM detects a high voltage condition, the EBCM turns OFF the system relay which removes battery voltage from the solenoid valves and pump motor.

Conditions for Running the DTC

The vehicle speed is greater than 8 km/h (5 mph).

Conditions for Setting the DTC

The system voltage is greater than 17 volts for 0.72 seconds.

Action Taken When the DTC Sets

If equipped, the following actions occur:
· The EBCM disables the ABS/TCS/VSES for the duration of the ignition cycle.
· The DRP does not function optimally.
· The ABS indicator turns ON.
· The Traction Control and Active Handling indicator turns ON.
· The DIC displays the following messages:
o Service ABS
o Service Traction System
o Service Active Handling

Conditions for Clearing the DTC

· The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
· The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

A possible cause of this DTC is overcharging.

JWingo

Thank you all for your help and advice. The code is in History. But it has occurred once before. I cleared it and all went well for about two weeks. So it is an intermittent condition. All grounds have been cleaned and coated with Di-Electric compound. I have recently replaced the alternator for a separate issue. Regulator showing off and one suspect bearing. Today on the way home from work I intentionally broke the rear tires loose. The Active Handling did just as it should. The code c1237 just kept in my mind. To produce that kind of voltage the alternator would have to be almost open or making an intermittent contact that seemed to be happening when I accelerate hard or maybe at other times too. The alternator was putting out 14.4 vdc. That seemed a slight bit high to me. I have a optima red Top battery. It’s around 6 months old and stays on a battery tender each weekend. With the car at idle, I only got around 13.4 vdc at the battery. Voltage drop from battery negative to alternator casing is .3. Voltage drop from battery positive to the positive alternator lug was 1.8. I raised the car and got to the starter. I have LG Long Tube headers so I’m sure some of you can feel my pain! Wanted to remove the main positive and the main charge wire to clean and inspect. Got out my sockets and no need for a ratchet! The bolt was slightly snug. I took it off with my fingers. I cleaned the three wires included on the post, coated with di-electric, reinstalled and tightened them per spec. Fired the car up and now the voltage at the Alternator is at 13.9 and the battery voltage is at 13.9. Voltage drop solved and hopefully the ABS issue along with it. I know these cars are very voltage sensitive. Cross your fingers for me.

trussme

you may have found the demon...a low supply voltage to the EBCM electronics can cause it to misread the system voltage level.

JWingo

I agree. Thanks to you all for your ideas and help. I'll keep you posted if the thing decides to resurface. Thanks!!