4G61 "Check Engine" light

A Lancer GSR with a 4G61 would be around '93, right?

Absolutely. You need an analog voltmeter or a 12V LED on 50cm of dual core wire. Find the diagnostic connector port under the dash, usually near the fuse box. Look in you owners manual for the location.

Connect across the diagonal corner pins. The LED solution is easier. When the engine is running normally, there's a continuous blink at about 3 Hz (or the meter needle swings). Errors are indicated by long (=10) and short (=1) blinks. So an error 24 is two long and four short.

Errors are output in order. You may have a code 11, 24 and 42 or similar errors.

Report back and I'll look them up. In the mean time, check the engine coolant temp sensor (two wire device) on the thermostat housing for damaged wires, also R/R the connectors on the aircleaner box, with some WD40.

You also should take out the ECU, open the can and check the big electrolytic caps for leaks or a fishy smell. If these let go they take the circuity board with them. They are easy to replace if you know how to use a soldering iron.

It's supposed to be 92, but there's a "Built Date" plate which says Feb 91.

Thanks indeed for all that info. It may be a week or two before I can get another good look at the car.

It could well be coolant temp sensor, and I may need to look no further than that. I replaced the thermostat not long before the problem started.

John

The sensor should look like this ( -- | ) with 6mm spades.

The connector on the harness is covered by a rubber hood. A common problem is that the connector does not mate correctly or completely with the spades on the sensor. The second common problem is the wire insulation hardens and cracks with age.

Also verify that your coolant level is correct.

Stewart DIBBS

I was allowed to look at the car for about 5 minutes today (son is always in a hurry).

The 2-pin sensor on the thermostat housing had much smaller connectors than the 6 mm spade type. It looked like this one:

Everything looked OK - no broken wires or signs of distress. We'll see if it we get another "Check Engine" now that it's been plugged in again.

I'm hoping to get the car again on Saturday to look for the diagnostic connection.

Yes, I'd already had a good look at that.

Thanks again,

John

There was an online site that had the entire service manual for a 91 posted. I have it on a different hard drive somewhere around here.

We found a connector block with 3 pins next to the fuse box. And we got regular pulses on an analog multimeter from the 2 pins furtherest apart.

We had to wait quite a long time (perhaps 70 or 80 pulses) before there was any variation in the pulse rate - so long that it got uncomfortable holding the leads onto the pins.

So for next time he comes over, I'm going to rig up a LED with resistor, diode and aligator clips so we've got a chance of recognising those variations accurately and counting them.

Am I right in thinking that there are 3 different pulse durations? "Standard" ones we ignore, with occasional bursts of longer and shorter ones to give the code?

John

Here's some code related "how to read them" pages:

GK

Thanks.

I've rigged up a little buzzer with alligator clips, which draws just 15 mA from a 12V circuit. As soon as I connected it, I heard a clear code "14" repeating constantly (maybe son had the multimeter probes in the wrong spot the other day).

From the above sites, I take it that's TPS (throttle position sensor). My Haynes manual says nothing about the TPS for EFI models, except to show it on a schematic diagram.

I'm sure I've located it on the car - A round device on the opposite side of the throttle body from the throttle cable termination, held on by 2 screws with some scope for rotational adjustment, and having 3 wires coming from the connector. The connector itself seems intended to be tamper-proof - it seems to be locked in place with a spring clip that I don't want to remove unless I have to. It looks like it might be difficult to reinstall.

Anyhow, I've given the connector block a good wiggle, so we'll see if the "Check Engine" light stays off this time. If not, I'll be back for advice about TPS faults. They seem to be not cheap.

John