Mechanics

EGR VACUME SWICH

1992 Isuzu Amigo

Electrical problem
1992 Isuzu Amigo 4 cyl Two Wheel Drive Manual 156000 miles

I have no vacume to the egr valve from the electrical vacume switch. I have tested the switch and it is good. What I have found is the two wire connector that goes to the switch has no ground signal on it's pin. The other pin registers 12 volts with the key on or motor running. Where does this pin get its ground? I assume it gets its ground signal from the ECU but now what componet or sensor is not telling the ECU to ground the switch thus allowing vacume through to operate the EGR valve.
I have tried a jumper wire at the EGR temp sensor thinking that It would be the ground source but no.
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Cheetahchrome
September 6, 2010.



Hi cheetahchrome,

Thank you for the donation.

The EGR solenoid is grounded by tbe ECU and it does not depend on 1 sensor to ground it. TPS, O2 sensor, ECT, EGR Temp Sensor etc are part of the system.

It is not grounded all the time and works only when required.

Why would you want to make it work?

KHLow2008
Sep 7, 2010.
California smog requires that the EGR system recirculates exhaust at around mid throttle. If its not opening the smog scanner machine fails the car.
I bought this car non-running thinking it had a blown head gasket and that I could fix and flip it.
Turns out the head was trash with two burnt valves.
Another 450.00 for head+ 80.00 on gasket set+ 95.00 to overhaul the four injectors. Now 68.00 for a failed smog, I'm in upto my neck for what the car is booked at.
When I first got it running after the head build, I had a hard check engine light. I pulled the code and the only one there was a code 32 for EGR temp sensor.
I pulled the sensor and it was carboned and sooty black. I cleaned it up with a brush and brake clean and the light went away. Thats when I ran it over to the smog shop to try and get a smog certificate, it failed. How can I bench test the EGR temp sensor?
Do I heat it with a flame or will boiling water work?
Am I looking for ohms Between the two pins or straight continuity?
I may me in over my head with this endevor trying to diag tech stuff using stone knives and bearskins, but I will probably have to keep this one.

Tiny
Cheetahchrome
Sep 7, 2010.
When vacumn is applied to the EGR valve with engine running, does the engine rpm drops or engine seem to flutter?

Did you test if the EGR valve is working and is it clogged?

Did you check if the EGR port under the EGR valve is clogged?

I am having problem getting the procedures for diagnosing Code 32 and might be able to get them only by next week if that is ok with you.

KHLow2008
Sep 8, 2010.
Yes, I've tested the EGR valve with bolh my fingers and with a Mity-Vac/pump/gauge. The motor starts to flutter and die. When I cleaned the EGR temp sensor tip I also pulled the EGR valve and cleaned/checked the ports. (I had a new gasket left from the head kit anyways). I'm sure I have a good vac source from the intake port and I've traced it on through the various other componets that are in line up to the EGR. The vac switch is where the vac source hits a dead end. It is the last hurdle before the EGR valve. The swich is not recieveing it's intermitent ground source from the ECU so that the vac source can go on to open the EGR.
THe shits huh?

Tiny
Cheetahchrome
Sep 8, 2010.
If everything is working correctly, the final part is to get a known good ECU to test.

KHLow2008
Sep 8, 2010.