Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSGMC1992JIMMY BASE, 2D UTILITY, 4.3 W, RWD, AUTOMATICREPAIR AND DIAGNOSISBRAKESTRACTION CONTROLANTI-LOCK BRAKE SYSTEM - 4-WHEELBLEEDING BRAKE SYSTEMELECTRO-HYDRAULIC CONTROL UNIT (EHCU)
1992 GMC Jimmy Base, 2D Utility, 4.3 W, RWD, Automatic
Electro-Hydraulic Control Unit (EHCU)
1992 GMC Jimmy Base, 2D Utility, 4.3 W, RWD, AutomaticSECTION Electro-Hydraulic Control Unit (EHCU)
NOTE:
It is not necessary to bleed EHCU during normal brake system bleeding. If EHCU is replaced, bleed EHCU first.
- Bleed EHCU after master cylinder and before wheel cylinders and calipers. Ensure ignition is off. Install 2 Combination Valve Depressors (J-39177) on High Pressure Accumulator (HPA) bleed valves. See Fig 1. Install one combination valve depressor on combination valve bleed valve. Turn 2 EHCU internal bleed screws 1/4-1/2 turn counterclockwise. See Fig 2.CAUTION: If internal bleed screws are left open, hydraulic fluid will by-pass accumulator and hydraulic pressure will be lost.
- Slowly apply brake pedal pressure and hold. Open left bleed screw on front of EHCU. See Fig 1. Leave left bleed screw on front of EHCU open until all air is expelled or brake pedal is fully applied. Close left bleed screw on front of EHCU. Wait 15 seconds. Repeat this step until all air is purged from EHCU, then close left internal bleed screw on EHCU. See Fig 2.
- Slowly apply brake pedal pressure and hold. Open right bleed screw on front of EHCU. See Fig 1. Leave right bleed screw on front of EHCU open until all air is expelled or brake pedal is fully applied. Close right bleed screw on front of EHCU. Wait 15 seconds. Repeat this step until all air is purged from EHCU, then close right internal bleed screw on EHCU. See Fig 2.
- Remove combination valve depressors from High Pressure Accumulator (HPA) bleed valves. Remove combination valve depressors from combination valve bleed valve. Ensure master cylinder fluid reservoir is full.
- Bleed wheel cylinders and calipers as necessary. Brake bleeding sequence is as follows: right rear, left rear, right front, left front. Use DOT 3 brake fluid only. Evaluate brake pedal feel and braking performance. Repeat bleeding procedure if necessary.
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.