engine won't crank

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amx1pxp
Posts: 54
Joined: Thu Mar 14, 2019 3:02 am

engine won't crank

Post by amx1pxp »

So my car won't start (2012 9C1). Since I have owned the car (about 3 years) it has always turned over slowly when starting, but would always fire up. After extended down time (due to my being constantly distracted while doing DOD delete) I finally started the car for the first time in nearly a year. Car started on first attempt, but cranked over real weak. Now won't crank at all. Usually get one click from the starter solenoid, but if I release the key and try again, there's nothing, no click, nothing.

So far I have:

1) Put a new in a new battery.
2) Removed starter/solenoid and performed bench test. Checked good.
3) Run a jumper cable from battery positive to terminal X2 (where the big cable goes) on the starter solenoid. No help.
4) Run a jumper from battery negative directly to engine block. No help.
5) Checked for continuity from body to engine block. Checks good.
6) Checked for 12V at X2 and that checks good.

and a few other things...

Service manual shows KR27 relay (R12CRNK) in start circuit. Relay is in X50A fuse block under the hood. Looking at schematic, it appears that with the key in the off position, of the 4 contacts, (30, 87, 86, 85) only 30 should have power. However, when I put my test light on each contact after removing the relay, the only contact with power is 87. Seems backwards to me. Looking at the illustration in the manual (photo attached) it would appear that 87 would be in the upper left position, 86 upper right, 85 lower left, 30 lower right. What am I missing here? I want to check for a good ground at 85 and make sure I have continuity from 87 to X1 at the starter but I'm afraid that if I get my contacts crossed I may inadvertently apply voltage to the ECM through 86 and then have real mess on my hands.

Have a lot of other thoughts but I'll wait and see if anybody has any clue what may be the problem. Looking at the schematic, it seems that if I were to jumper 30 and 87 (relay removed) engine should crank, regardless of key position. Don't yet have the stones to do it with my being confused about which contact is which. I believe if I disconnect X102, should take the ECM out of the picture and allow me to be a little more aggressive with my checks....

Attached are 3 pics from the manual.
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bstoner
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Re: engine won't crank

Post by bstoner »

1. If you give +12v to the starter solenoid does it turn over/crank ok? If yes continue to #2. If not then bad starter/solenoid, battery, ground, or main power cable. Starter could be bad but bench test good.

2. Have someone turn key to start position. Do you get 12v at the solenoid indicating the car is signalling the starter to turn over?
2014 Caprice PPV, 6.0L, BTR Stage 2 Cam, 3.45, 3" exhaust, Rotofab intake, Chris Henry tuned, future LSA....
amx1pxp
Posts: 54
Joined: Thu Mar 14, 2019 3:02 am

Re: engine won't crank

Post by amx1pxp »

I did do your test 2, but was without help and so had to rig my multimeter and jumper wire to the connector that goes to the solenoid. Turned the key and did not see 12V but not sure I had my jumper wire inserted far enough into the connector. Have to wait until next week to try again - car is at our other place out in the country.

Still banging my head against the wall about the contact labeling in service manual diagram (fuse block X50A). I'm seeing power at 87. According to schematic, should be contact 30. I must be reading something the wrong way.

When I'm out there next week I'll try and put power directly to the solenoid and see what happens.

Thanks for weighing in...
BluesBro
Posts: 134
Joined: Tue Aug 03, 2021 1:26 am

Re: engine won't crank

Post by BluesBro »

Had similar issues with weak crank/no crank.

Starter tested good, but was certainly the problem.

Got a new acdelco unit from rock auto and problems have never reoccurred.

On a side note, new acdelco starter was manufactured in japan by mistubishi, which I found interesting.
2014 Caprice PPV 6.0L - TSP Stage 1 Cam, Solo 3in Mach Cat Back, VCM OTR, Pedders Coilovers, HP Tuned
2002 Avalanche 5.3L - MBRP Exhaust, RC 6in Lift
amx1pxp
Posts: 54
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Re: engine won't crank

Post by amx1pxp »

I see re-manufactured AcDelco "Gold" unit made by Mitsubishi. Did that thing come with the solenoid attached? Did you replace the whole assembly together, or just the starter?
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Mooseman
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Re: engine won't crank

Post by Mooseman »

Make sure you have constant 12V+ at 30 or 87 at the relay. Try jumping 30 and 87 on the relay. If it cranks, the starter is good. If not, it's bad.

If not getting 12V+ at the relay 30 or 87, check fuse and wiring. Check for 12V+ constant at the 40A fuse F8UA.

If all the above checks out, you must check that the relay at 86 is getting the 12V+ signal from the ECM. If it's not sending the signal, the ECM is not happy, possibly because of the Park/Neutral switch or another condition preventing it from doing so.

Go from the results.
2011 Caprice PPV, former RCMP test vehicle, never put into service
Build Thread: http://www.newcaprice.com/forum/viewtopic.php?t=2419
amx1pxp
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Re: engine won't crank

Post by amx1pxp »

I agree with your suggestions completely, but once again am baffled by the fact that I have power at 87 but not 30. According to the diagram, should be the other way around. I understand that 30 and 87 are opposite poles of a switch. When there is continuity between the two, things happen. Same with 86 and 85. However, with respect to 86 and 85, one goes to ground, the other to the ECM. When I probe these contacts with my multimeter, I am either applying voltage to the terminal to look for a ground at 85 with (the meter on the resistance setting) or, looking for voltage from the ECM at 86. If I get them mixed up, I either fry the ECM, or fry my multimeter because it's on the wrong setting. Are 87/30, 85/86 interchangeable? How could that be?

I'm all ready to jumper 30 and 87, just want to be sure I know which contact is which. What the X50A illustration shows, and what my test light show, are at odds (test lamp lights on 87, nothing at 30)
Sanford
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Re: engine won't crank

Post by Sanford »

Is the fuse that powers up terminal 30 good? The only way terminal 87 is going to be hot is if the starter solenoid plunger pulled in and stuck, the contacts welded together in the solenoid, the solenoid wire is shorted to the battery cable in the engine harness or an upfitter did some funny, anti-theft trickery.
amx1pxp
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Re: engine won't crank

Post by amx1pxp »

Fuse F8UA is good. Pull it, and power goes away from 30 (or is it 87?)

I had the exact same thought as you, but in that case, both 30 AND 87 would be hot.

Thanks for all the help guys. I have several different avenues to check this out when I get back to the car next week.

Just want to be sure that the lower right contact of the R12 relay (when viewed from the front of the car, facing the firewall) in fuse block X50A is, in fact, contact 30.
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Mooseman
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Re: engine won't crank

Post by Mooseman »

Is it possible that you're looking at the relay upside down/backwards? It can be confusing when looking at the bottom of the relay and transposing this to the relay socket.

It's also possible that the schematic has it backwards. Wouldn't be the first time.
2011 Caprice PPV, former RCMP test vehicle, never put into service
Build Thread: http://www.newcaprice.com/forum/viewtopic.php?t=2419
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