check engine light

Hi,

It sounds like you may have two issues. The first thing I would like to do is check for diagnostic trouble codes. This vehicle has an OBD1 system that doesn't require a scan tool.

Follow the directions in this link and let me know what codes are found:

https://www.2carpros.com/articles/suzuki-code-retrieval-and-definitions-1986-1995

I will watch for your reply.

Take care,

Joe

Hi,

Thank you for the reply. With key on, engine off and NO check engine light illuminated. The ECM will not flash anything. The light must be on first. Yes, I tried to retrieve something by jumping the diagnostic connector by the battery. Nothing happens. Thank you for the help.

I find it curious that the O/D light flashes, but only when the check engine light is not on.
There is no pattern to the O/D light flashes, just steady, flash, flash, flash.

The manual I have "sic" only says to diagnose the check engine light circuit if the light is not on.

I will try the fuse option and see what happens.
Thanks again.
Stay tuned, Curt

Hi,

If you are jumping B and C in the connector, that's how it's done. I attached directions from the manual for you just to confirm how it's done.

Additionally, the remaining pics are diagnostics. See if they help.

Let me know.

Joe

See pics below.

Monday May 9.
Hi, thank you for the diagrams and pics. What a huge help.
I searched the internet for the flow chart, but with no luck.
Then I stumbled upon 2CarPros.
Bless you all.
I'm a full-time caregiver to my mom so time with car is limited and the weather here in Tri-cities WA., has been rainy.
Looks like this Wednesday is car day for me.
I'll post what I find later in the day.
Thanks a bunch. Curt.

Hi,

You are very welcome. I'll watch for your reply.

Take care,

Joe

Morning, sorry I did not get to the Suzuki.
Weather here windy-cloudy-rainy.
I'm working in the driveway, so it looks like Sat-or-Sun.
Thanks, Curt

Hi,

No problem whatsoever. Thanks for letting me know. When you do get it, let me know if I can help in any way.

Take care,

Joe

Monday 16
Hi, I got the main relay checks done as per the diagram pictures you sent.
Battery voltage is present where it should be. At the relay and wiring harness plug both shows B+ voltage.
the relay clicks and I can feel it as well in my hand when turning the key to run position.
I fallowed the flow (yes-no) chart twice and got the same results.
Poor connections at A12 and A13-OR-ECM and it's circuit.
I inspected the plug ends and carefully, bent-let's-say, the connections for A12 and A13 to ensure a tight connection.
No corrosion visible in any way.
upon repeating the flow chart test, I got the same results.
..."check ECM circuit"...
I'm going to check all grounds and battery positive voltage where I can find them.
Like,....
B+ at ignitor
ECM pin #A1 for B+
ECM grounds at B1--B2--and--B14
grounds under hood for B+ and any voltage drops.
When I get some real numbers I'll respond. Thanks for the help.
I'm still thrown by the O/D light flashing though.
Curt

Hi,

Sounds like you have been busy. As far as the grounds are concerned, I tried finding them for you. Because of the model year, they are not listed in my manuals.

Let me know what you find.

Take care,

Joe

May 17,
Hi. I got some real numbers.
Static battery voltage=12.55 VDC.

6-grounds in engine bay=12.54-to-12.55 VB+.

Full battery voltage at both sides of all fuses (under dash) with key on.

Battery voltage at main relay=12.55 at terminals A-B-C.
Voltage at D=0.80 VDC (back probe blue wire A10 with key on, relay connected to harness plug).

Battery voltage at ECM pins.
A1=12.55 VDC
A22=10.70 (cranking VDC).

I looked closely at ECM wires A10-A12-A13, all appear tight and clean.
This ECM is a replacement some three years ago for the OEM unit.
During that time the car always started, ran and drove without issues.

At this point I'm condemning the ECM. Looks like it is not completing the ground circuit inside the ECM itself. (Is this conclusion correct? As the main relay is working.)
What say you?
Did I miss something?
Curt

I found this on the internet.

I have this picture as well. Note that cavity pin A10 claims B+ voltage should be 0.50VDC or less. I got 0.80VDC. The main relay "clicks" when turning the key to run. So, is ECM working properly then? If so, then why no CEL light and, OD/Off light blinks.
I looked for TCM diagnostic plug so I could "jump" it and retrieve any codes. No plug exists.
I'm stumped.
Curt

I cannot find a diagnostic flow chart for just the CEL circuit. The Chilton manual I have for Suzuki's just says "If no CEL is lit with key on then diagnose the circuit. But no details. It is not a burned-out bulb as I can make it come on by using the Noid light reset switch.
Any ideas would help. Thanks, Curt.

Hi,

Does it indicate "B+"? That indicates battery voltage at the battery itself, so it should be 12v.

As far as the OD light, do you remember having any specific issues with the transmission? For example, did you notice slipping?

Let me know.

Joe

Well, I'm understanding that it means voltage output from ECM at blue wire to main relay should be 0.50 VDC. I do not know what it should be.
You're saying it should be FULL battery voltage?
There have been zero issues with the automatic transmission since 2013 when I got the car.
The OEM ECM acted up badly some three years ago, then the transmission was wonky but only because of the bad ECM. Once I replaced the ECM the transmission operated without issue.
Thank you for the help.
Curt.

The last picture I posted is of the wiring harness at the ECM. The person who posted it claims that those are the voltages one should be seeing at the harness when probing it.

Based on what you are telling me, it does seem there is an internal short in the ECM. I do have a question. I looked at the last pic you sent. A10 shows 0 and not B+.

Everything I have been taught has always indicated B+ is the direct battery power supply. I'm not sure what the other person is indicating.

Let me know.

Joe

Hi and Thank You for your help.

Hi. Yes, you are correct, as per that line of the chart. But the *(asterisk) by the 0 is all important.
At the bottom of the chart said the asterisk reads that voltage should be less than 0.50.
When I probed the main relay A10 (blue wire from ECM), key on, I got 0.80 volts.

So, what is that telling us??

Voltage to and from main relay are correct? Or not?

Question, with key on and main relay connected, and ECM connected to wiring Harness how much voltage I should see at main relay terminal B and D.

I know that with the main relay disconnected and blue wire (which is A10 at ECM wiring harness plug) grounded, I get full battery voltage at ECM wiring harness terminals A12 and A13.

Sorry, in reference to sentence three above, the relay and ECM are both plugged in to their respectful wiring harness plugs.

Hi,

I just read through the schematic again. When the key is placed in the run position, pin A10 at the ECM provides a ground path allowing 12v to actuate the relay. When this happens, the relay closes, and power is sent to A12 and A13. Based on what I am seeing, there should be 12v. Is that what you are getting? I see no resisters that would lower that voltage.

Let me know.

Joe

See pic below.

Hi, voltage at ECM pins A12-&-A13 is indeed full battery voltage.

If it helps.
This "No Check Engine Light" condition has been quite Sporadic over the last 6-8 months.
The last time I drove it, I made 9-stops. The last one failed to start.
Now it's all the time.

Sorry Joe, I did not mean to be confusing to you. Thanks for the help. Curt

The Voltages I posted on May 17 at 3:13 PM are correct and are what I am getting when probing.

The A10 pin from the PCM provides a ground path. It receives 12v when the PCM signals it closed. So, if you checked that circuit, you shouldn't have gotten power unless the relay was in place. So, based on what you are saying, everything is correct and should work as designed.

I have one more question before I say the ECM is the likely cause. If you remove the relay and check pin A10 for continuity to ground with the key off, what do you get?

Let me know.

Joe

Hi, I will double check what you have suggested.
Check pin A10.

Hi,

Key Off,
Remove Main Relay,
Probe Blue Wire at Said Relay to Ground,
Ohms=3.283 million,
Plug Relay in and turn on key,
Voltage=0.80 VDC.
If it helps, the fuel pump relay is not being activated when key in in run position.
I can make the fuel pump run (listen to fuel filler) and Fuel Pressure is present at Rail.
I do have a test (yes-no) chart in my service manual that I performed twice just to be sure I was doing it correctly.
The net result was open circuit in ECM.
Thank you for your patience on this.
Curt

Curt,

You are very welcome. Could you let me know if this takes care of the issue?

Let me know.

Joe

Okay, well I did not replace any parts as of yet. So, I'm not understanding your question.
If I'm preforming tests on main and fuel relays correctly, then the ECM is faulty.
I'm going to look for another ECM, plug it in and see if it runs.
If the car does not run, then I'm going to sell it and move on.
For giving your time to a stranger, until you're better paid.
Thank you and may the day be smooth.
Curt.

P.S.
A great web site you all have here and a welcome service to the public.

Curt,

The ECM should complete the circuit from the relay (A10). It doesn't sound like that is happening. So, it seems the ECM is suspect.

Regardless, please let me know how things turn out for you. You are welcome for anything that I was able to provide, but I feel like a failure.

If I don't hear back from you, please feel free to come back anytime in the future. You are always welcome here.

Take care,

Joe

It's all good.
Trying to accurately diagnose any drivability sight unseen is a challenge in itself.
You responded to the information you were given.
Yes did good.
Curtis

Hi, I installed a remanufactured ECM. Key on, all dash lights on, starts and runs great. Open and closed loop both function they should.
Curt.

Curt,

Excellent. That is good news and I'm sure you are happy. LOL

You take care of yourself and please feel free to come back anytime in the future. You are always welcome here.

By the way, great job.

Joe