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John, GMC Technician
Category: GM
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Experience:  ASE MASTER TECHNICIAN/40 years experience
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1998 GMC c2500: No check eng light, does crank - wont start

Customer Question

1998 GMC C6500 Cat Motor - No check eng light, does crank - won't start
Submitted: 4 years ago.
Category: GM
Expert:  John replied 4 years ago.

Hello & Welcome to JA,

Make sure you have a check engine light on in the instrument panel cluster when the key is first turned on.

 

Have you scanned the data from the computer ,does it show an rpm signal when the engine is cranking ?

 

Here is a trouble chart to test the transfer pump system.

Fuel System Diagnosis (Fuel Transfer Pump Inoperative)

Step

Action

Value(s)

Yes

No

1

  1. Turn the ignition switch to the RUN position.
  2. Backprobe the fuel transfer pump relay with a test lamp from cavity 85 to ground.

Does the test lamp light?

--

Go to Step 2

Go to Step 5

2

Backprobe the fuel transfer transfer pump relay with a test lamp from cavity 30 to ground.

Does the test lamp light?

--

Go to Step 3

Go to Step 5

3

  1. Turn the ignition switch to the LOCK position.
  2. Disconnect the fuel tank control module.
  3. Connect a fused jumper from the dual fuel tank control module connector cavity D to ground.
  4. Turn the ignition switch to the RUN position.

Does the fuel transfer pump run?

--

Go to Step 4

Go to Step 6

4

Replace the duel fuel tank control module.

Is the repair complete?

--

System OK

--

5

Locate and repair open in CKT 139 (PNK) between S417 and the fuel transfer pump.

Is the repair complete?

--

System OK

--

6

  1. Leave the fused jumper connected.
  2. Backprobe the fuel transfer transfer pump relay with a test lamp from cavity 85 to cavity 86.

Does the test lamp light?

--

Go to Step 7

Go to Step 12

7

  1. Backprobe the fuel transfer transfer pump relay with a test lamp from cavity 87 to ground.
  2. Turn the ignition switch to the RUN position.

Does the test lamp light?

--

Go to Step 8

Go to Step 13

8

Backprobe the fuel transfer transfer pump with a test lamp from cavity B to ground.

Does the test lamp light?

--

Go to Step 9

Go to Step 14

9

Backprobe the fuel transfer transfer pump relay with a test lamp from cavity A to cavity B+.

--

Go to Step 10

Go to Step 11

10

Replace the fuel transfer pump.

Is the repair complete?

--

System OK

--

11

Locate and repair open in CKT 350 (BLK) between G408 and the fuel transfer pump.

Is the repair complete?

--

System OK

--

12

Locate and repair open in CKT 497 (LT GRN) between terminal 86 in the fuel transfer pump relay socket and terminal D in the dual fuel tank control module harness connector.

Is the repair complete?

--

System OK

--

13

Replace the fuel transfer pump relay.

Is the repair complete?

--

System OK

--

14

Locate and repair open in CKT 120 (GRY) between the fuel transfer pump relay and the fuel transfer pump.

Is the repair complete?

--

System OK

 

 



Edited by john on 7/1/2010 at 2:48 AM EST
Expert:  John replied 4 years ago.

Check this engine shut down coolant sensor & connector.

 


Engine Harness, Upper Right Front View


Object Number: 590114  Size: LF
Click here for detailed picture of above image.

(1)Engine Harness
(2)Engine Coolant Temperature (ECT) Switch (for Check Gages indicator)
(3)Air Conditioning (A/C) Compressor Clutch Connector
(4)Generator Fuse
(5)Automatic Engine Shutdown Engine Coolant Temperature (ECT) Switch

Customer: replied 4 years ago.
has no electric transfer pump, does not have duel tanks. no check eng light will not start. and can not communtcate with PCM. this is a dmp truck. when check eng light comes on it will start, when it does not come on it will NOT START.
Expert:  John replied 4 years ago.

I will opt out & have your question re listed so another expert can possibly help you.

I hope you have a good day.

Customer: replied 4 years ago.
Relist: Inaccurate answer.

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