Truck not turning over

[1998_K1500_Sub]

... it looks as if it may have had a “factory?” Secondary battery installed, which is no longer there. Could that solenoid with the missing cable be for that?

Yes. My 1998 Suburban has a 2nd battery installed for camping use, and I have an isolation relay just like yours.

The dealer did it, not factory, in my case.

 

[Kevin99]

Yes. My 1998 Suburban has a 2nd battery installed for camping use, and I have an isolation relay just like yours.

The dealer did it, not factory, in my case.

Thats good to know thanks, do you happen to know where the 2 small cables (1x black, 1x brown) go to from the solenoid? I don’t want to remove it if it might knock something else out.

 

[1998_K1500_Sub]

Thats good to know thanks, do you happen to know where the 2 small cables (1x black, 1x brown) go to from the solenoid? I don’t want to remove it if it might knock something else out.

Probably the black one leads to a ground point (frame, body) and the other to the switched +12 from the ignition key switch.

 

[Russ B]

I have a 1989 K1500 5.7 the second picture appears to be the oxygen sensor connector.

 

[Russ B]

The setup is not factory. Since this post appears to be from UK, it is possible owner might not have been able to get a GM starter so he attempted to fix it externally with a Ford external solenoid or someother starter that fit. I would be curious to see the actual starter setup. On my GM a small purple wire goes to the starter solenoid mounted on the starter. To activate the starter, power from the ignition switch goes to that purple wire to move the starter bendix clutch which also turns the starter motor.

To test a starter jump/hotwire the purple wire to the big positive cable on the starter with a screwdriver or another short piece of wire. Otherwise pull the starter and get it tested.

 

[Kevin99]

The setup is not factory. Since this post appears to be from UK, it is possible owner might not have been able to get a GM starter so he attempted to fix it externally with a Ford external solenoid or someother starter that fit. I would be curious to see the actual starter setup. On my GM a small purple wire goes to the starter solenoid mounted on the starter. To activate the starter, power from the ignition switch goes to that purple wire to move the starter bendix clutch which also turns the starter motor.

To test a starter jump/hotwire the purple wire to the big positive cable on the starter with a screwdriver or another short piece of wire. Otherwise pull the starter and get it tested.

You’re absolutely correct, the starter has its own solenoid attached as you say is standard, the purple wire is attached to the S terminal the main starter cable from the battery goes to the main stud on the starter as expected.
I’ve pulled the starter and bench tested it and it its dead. I’ve got a new GM starter being shipped over this week.
One thing that has thrown me is this, when the starter was in the engine on start there was this clunk sound from what i thought was in the engine bay, once the starter was removed i turned the key to the start position and this clunk sound could still be heard. I was expecting no noise at all once the starter had been removed. Any idea’s?

 

[Schurkey]

As I said in Post 10: Likely an accessory solenoid not related to the starter motor.

My '97 K2500 has a similar solenoid for the snow plow.

 

[Kevin99]

Hi I have 1992 C2500 Silverado 350,
I replaced the battery with a brand new one today, now when i turn the key it doesn’t turn over, just click / clunk which seems to be coming from the solenoid. When i turn the ignition on to the start position the battery gauge now climbs to just over 10 or 11 volts, previously it would be around 13 volts on starting.
Im guessing it may be the solenoid but the wiring on the solenoid does not match up to any wiring diagram i’ve seen.
When trying to trace the wiring I found the purple wire (in the second picture) was disconnected and could not see anything it could connect to
Im located in the UK so support for this truck is pretty nonexistent, so any help and advice would be much appreciated.

Update, it was the starter and a couple of faulty grounds, new starter, couple of new ground leads, new set of plugs and she now fires up 1st time.
Thanks everyone for all the advice. Appreciate it .