1990 Volvo 740 wagon GL won't start

Lady Selina · Post by **Lady Selina** » 19 Mar 2011, 18:53

Okay here it goes. I have a 1990 740 GL Wagon with the Regina engine that will not start. I have replaced the distributor and the cap, the ground wires and the plugs and wires, plus the ignition coil. The starter engages just fine. The fuel pump is working properly and the power stages are good. I get spark and everything. I have ran the diagnostic and it keeps coming up 3-2-1 cold start ground missing or short. I have checked and triple checked the wires. if anyone knows something I would be so very thankful.

Post by **billofdurham** » 20 Mar 2011, 12:39

Welcome to Matthew's Volvo Site.

it keeps coming up 3-2-1

Are you clearing the code each time?

Further checks that can be made are:

Switch off the ignition, disconnect the cold start valve and check, with an ohmmeter or multimeter, between terminal 1 on the connector, right hand side as you look at it. You should get infinite resistance if it is earthing (grounding) OK.

If that test is OK check the cold start valve itself with an ohmmeter between the two terminals on the valve. You should get 10 ohms. If you don't get 10 ohms the cold start valve is faulty.

If you get 10 ohms switch on the ignition with the sensor disconnected and check from terminal 1 on the connector and earth. you should get battery voltage.

Bill.

Lady Selina · Post by **Lady Selina** » 21 Mar 2011, 13:58

test was normal... not that.

clearing code every time.
any other suggestions?
i'm willing to try anything right now

OLD IS GOLD · Post by **OLD IS GOLD** » 09 Apr 2011, 09:50

You established spark, now check voltage to fuel injectors. Use Volt meter or test lamp across any one of the four fuel injectors plug. You will need to have meter or lamp connected while cranking engine to see if voltage pulses on and off.

Post by **jonesg** » 11 May 2011, 23:09

"Okay here it goes. I have a 1990 740 GL Wagon with the Regina engine that will not start. I have replaced the distributor and the cap, the ground wires and the plugs and wires, plus the ignition coil. The starter engages just fine. The fuel pump is working properly and the power stages are good. I get spark and everything. I have ran the diagnostic and it keeps coming up 3-2-1 cold start ground missing or short. I have checked and triple checked the wires. if anyone knows something I would be so very thankful.
Lady Selina "

Swap the 2 relays on the coolant tower. One controls the injectors. They fail often enough.

Post by **billofdurham** » 12 May 2011, 12:03

An idle air control valve or motor (IAC) is designed to adjust the engine idle RPM speed by opening and closing an air bypass passage inside the throttle body. The cars computer or electronic control module (ECM) receives information from various sensors and will output signals to adjust the IAC motor in or out to adjust engine idle speed by controlling engine idle air. An IAC motor can fail one of two ways, either the motor short circuits and stops working or the motor will develop high resistance and cause the IAC control motor to react slowly, either failure can cause the engine to stall at idle. When a trouble code scan is performed it sometimes won't always detect a failed or weak IAC motor. To check the IAC motor remove the unit, with the wires connected turn the key to the "on" position without starting the engine, the IAC should move in or out. If the IAC motor does nothing it has probably failed, replace it with a new unit and recheck system. Note: while the IAC motor is removed clean the passages the IAC uses to control idle air speed, using aerosol carburettor cleaner, also inspect the IAC for a build-up on the seating (pointed) end and clean as necessary.

In theory the IAC should not cause a no start situation but it is possible that the idle speed is too low to allow the engine to catch.

Have you tried clearing the code and trying to start the engine?

Bill.