Question about 1986 Chevrolet Chevy

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Electric vacuum pump has six wires, where do they go

F100 with a 6.2 deisel motor just replaced. bought an electric pump to boost the brakes. mechanic couldn't make it work. auto electrician scratching his head. motor imported from States, out of a hummer. vacuum pump falso imported rom Fort Worth.

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You might be looking at an air suspension pump. it is not designed to work for long periods of time.

Posted on Jun 02, 2009


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How to fix 17887/P1479 brake boost vacuum and 18033/P1625 powertrain data bus?

I would go to the data bus first. No easy fix for this. You need a scanner( not a code reader) to trace this down. You also need wiring schematics and pin outs for the plugs. And a volt/ohm meter. after that issue is fixed. If you still have the booster problem, replace the vacuum pump.

May 08, 2016 | 2004 Volkswagen Touareg

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I have hard breaks on my 1988 lincoln mark vii and my abs light stays on any help

Bad vacuum brake booster test booster by shutting car off and don not touch pedal open hood and remove hose to booster a wooosh sound should be heard if not need a booster.

May 13, 2014 | 1988 Lincoln Mark VII

1 Answer

Brakes get hard and no vacuum from motor

The pump boosts engine vac so yes it could be a failing pump.
You could also have a hose that is collapsing inside.

May 10, 2013 | 1983 Cadillac Eldorado

2 Answers


The power brakes vacuum booster... may have a vacuum leak. you can check it with an engine vacuum meter, or remove the rubber hose from the booster and plug it.. and see if the engine changes pase, idle smooths out, revs a bit higher, etc. noticeable change in engine idle would confirm a leak.

Oct 01, 2012 | 1990 Lincoln Mark VII

2 Answers

When antilock brake and brake lights are on and pedal is hard to push and stop.What is typical on a 1990 lincoln mark seven

The hydraulic brake booster on a late model Mark VII and early Continental, is very different from most. It is equipped with something known as a "TEVES" brake system. I'll attempt to teach you what does what and why, so you won't spend a ton of money just because you and maybe your mechanic aren't familiar how it works. The way it's always been is,..."if you don't understand it...replace the whole thing"! The problem with using this technique is, unless you want to spend $2K for the whole thing, your going to be buying a used system....which may not be a whole lot better than the one you have now.
The main parts in the system that we will discuss include an ACCUMULATOR, a HYDRAULIC PUMP, a hydraulic pump RELAY, and a PRESSURE SWITCH. These are the key players in this operation.

HYDRAULIC PUMP MOTOR= Underneath the brake assembly (2 pin connector) Hydraulic pump motor
RELAY = On the drivers side strut tower
PRESSURE SWITCH = 5 pin connector facing the # 7 or 8 spark plug(drivers side)
ACCUMULATOR = Round black ball on the drivers side

HYDRAULIC PUMP MOTOR is an electric hydraulic pump used to "boost" pressure for the brake assembly. This pump is $900 new!
hydraulic pump motor RELAY is just what its sounds like. It gives the hydraulic pump motor power to come on.
PRESSURE SWITCH is the "brains" in the system. It senses how much pressure is "on line", and when the system needs more pressure, it tells the relay to "power up" the hydraulic pump motor.
Another one of its jobs is to turn on the RED BRAKE LIGHT, then the ANTI-LOCK lights to alert the driver that the pressure is dangerously low. (The reason the anti-lock light comes on, is because the ABS cannot fuction if theres a problem with the manual brakes)
ACCUMULATOR stores energy or pressure like a reservoir. Its there so the hydraulic pump motor only has to come on every 3rd or 5th time. Its design is more complicated, but basicaly the same principle as an air tank on a compressor.

What usually happens is, in time, the accumulator gets weak with age and can't hold the pressure like it was designed too, and therefore, the hydraulic motor comes on every time the brakes are applied....rather than every 3rd or 5th time. This means all these parts are working 3 or 5 times more than they were designed to. This puts an extreme amount of pressure on an already old system.
What we know from this is, the accumulator needs replacing because it's what started all this, but now the pressure switch and relay needs replacement also because it has worked overworked.
NOTE: always replace the relay when replacing the pressure switch. The relay came on every time the pressure switch told it too, so if one is worn out....the others not far behind!

Jun 08, 2011 | 1990 Lincoln Mark VII

2 Answers

Vacuum leak sort of sound coming from the general area of the vacuum booster on my 1981 Ford F-150 w/ 300"six cylinder and 4sp. It stops when I apply the brakes fully.

check the hose and the rubber around the vacuum booster the best way i found a leak was to
take a 3ft peace of fuel line and put 1 end up to my ear and take the other end and probe
around the motor or ware ever i could here a vacuum leak you don't have to use fuel line any hose will do

i hope this helps you

May 24, 2011 | 1981 Ford F 150

2 Answers

Turbo/supercharger under boost

Turbocharger under boost problem:
The car goes in "limp mode"!!!
After scan the EDC-15P engine control unit with a VAG or KTS -BOSCH diagnosis tool you will find this DTC - Fault code: P1557-Turbo Boost pressure control exceeded
1. Engine stopped and ignition switch off. Check all pneumatic connections and hoses between turbocharger actuator = pressure unit for boost-pressure control, boost-pressure control solenoid valve, vacuum reservoir, EGR control solenoid valve, intake-manifold flap solenoid valve, EGR valve with throttle - part of intake manifold. Also the vacuum connection between tandem pump and brake booster. If you find something wrong replace parts. If not go to step 2.
2. Extract the hose of the turbocharger actuator = pressure unit for boost-pressure control part of turbocharger. Instead of the original hose you must place another 1 meter long hose with the same inside diameter, and then you check to inspire yourself the air from the other one extremity of this hose. The mechanical connecting rod of the turbocharger actuator must have a smooth and whole motion. If you can do that with your mouth, then you must replace the boost-pressure control solenoid valve. If you can not reach this with your mouth, then you go to step 3.
3. This is the most difficult work. The problem is that the soot particles deposits inside the turbocharger plugging the variable nozzle geometry mechanism = adjustable vanes of the turbine. If the turbocharger actuator is not able to adjust the turbine vanes the charge air pressure increase too much and ECU (engine control unit) go in "limp mode" = engine protection software. As a result the "limp mode" engine still running until you turn the engine off (ignition switch off) and back on when the "limp mode" is deactivated, but the fault still remain in ECU memory!
4. You must be able to extract the turbo from the engine and then to disassemble the turbocharger, clean inside adjustable vanes mechanism and refit all.

Aug 19, 2010 | Audi A4 Cars & Trucks

2 Answers

Boost(?) problem audi tt

It is probably either the N75 valve(Diverter Valve) or the wastegate actuator. Usually a significant boost leak will set a DTC, still check all hoses and clamps.

A bad wastegate actuator or flap would cause no boost but not necessarily the air-sound.

Testing N75

Air Bypass Valve: Testing and Inspection
With Generic Scan Tool
Wastegate Bypass Regulator Valve, Checking
Recommended special tools and equipment e.g.:
- VAG1526 multimeter or VAG1715 multimeter
- VAG1594 connector test kit
Test sequence
- Switch ignition off.
- Disconnect connector at solenoid valve for boost pressure regulation.
517f5c6.jpg - Measure resistance between terminals of valve.
Specified value: 25...35 Ohm
If specified value is not obtained:
- Replace Wastegate Bypass Regulator Valve -N75-.


Testing N249

Exhaust Bypass Valve: Testing and Inspection
With Generic Scan Tool
Recirculating Valve For Turbocharger, Checking
Valve opens between connection to intake manifold and connection to deceleration shut-off valve with no voltage. Connection to vacuum
reservoir is closed.
Test sequence
- Switch ignition off.
- Disconnect connector from Recirculating valve for turbocharger -N249-.

9dfbfb9.jpg - Measure resistance between terminals of valve.
Specified value: 27...30 Ohm
If specified value is not obtained:
- Replace Recirculating valve for turbocharger -N249-.
If specified values are obtained:
- Connect test box to control module wiring harness, connect test box for wiring test.

1a741bd.jpg - Check wire between test box socket 105+2-pin connector terminal 2 for open circuit according to wiring diagram.
Wire resistance: max: 1.5 Ohm
- Also check the wire for short circuit to B+ and Ground (GND).
If no malfunctions are found in wire:
- Check wire between 2-pin connector terminal 1 and the Fuel Pump (FP) Relay -J17- for open circuit according to wiring diagram.
Wire resistance: max: 1.5 Ohm
If no malfunctions are found in wires:
- Replace Engine Control Module (ECM).


To test the wastegate, locate the wastegate linkage rod and verify that there is no play and that it is closed. You can apply compressed air to the actuator to see if it opens and closes. (not more than 30 psi)


Vehicle: Vacuum and Vapor Hose Diagrams
System Diagram
Vacuum Diagram
1 From fuel tank
2 EVAP canister
- with Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-
3 Check-valve for EVAP canister
- Between EVAP canister and intake manifold before turbocharger Installation position (light/dark side): Arrow points in direction of flow, as
4 Turbocharger
5 Pressure unit for boost pressure regulation
6 Mechanical recirculation valve
7 Brake booster
8 Check-valve
- Between brake booster and intake manifold
- Installation position (light/dark side): Arrow points in direction of flow, as shown
9 Wastegate bypass regulator valve -N75-
10 Mass Air Flow (MAF) sensor -G70-
11 Air cleaner housing
12 Pressure control valve for crankshaft housing ventilation
13 Vacuum reservoir
- Bolted on at cylinder head
14 Charge air cooler
- With charge air pressure sensor -G31-
15 Fuel pressure regulator
16 Throttle valve control module -J338-
17 Intake manifold
- With Intake Air Temperature (IAT) sensor -G42-
18 Crankcase ventilation
19 Check-valve
- Installation position (light/dark side): Arrow points in direction of flow, as shown
20 Recirculating valve for turbocharger -N249-
- Component location Fig. 1
21 Check-valve
- Between EVAP canister and intake manifold
- Installation position (light/dark side): Arrow points in direction of flow, as shown
22 Charge air cooler

Oct 01, 2009 | 2004 Audi TT

1 Answer

Oversize CAM on rebuilt 302 & reduced vacuum to breaks

Ran into this problem the same way you did, but back in '75 with a Ford 289.
First of all,and you've probably done it already, is to make CERTAIN all vacuum hoses and connections, tees etc. are leak free. Then move on to diaphram actuated valves (egr valve, heater core valve, vacuum modulator valve, distributor vacuum advance.... and then there's the diaphram actuated dampers for a/c and heat in the dash) ALSO, a good idea is to add a larger than stock vacuum canister, such as a large coffee can - metal of course!

Jan 16, 2009 | 1965 Ford Mustang

2 Answers

1980 ford f700 electric brake pump operates when pedal is depressed while vehicle is running and driving

check you aux hydurlic pump, ford will have one pump for the powersteering and one on the right hand side for the brake

Jul 15, 2008 | 2007 Ford F-450 Lariat

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