1991 Caprice Classic Wagon ABS problems

Discussion in 'General Automotive Tech' started by Darth_Sidious69, May 5, 2017.

  1. Darth_Sidious69

    Darth_Sidious69 New Member

    Joined:
    May 5, 2017
    Messages:
    6
    Likes Received:
    2
    Trophy Points:
    1
    Hello all.
    From time to time the antilock lights up at irregular intervals.

    Last week I finally found someone here in germany who has a diagnostic tool with an OBD1 adapter.

    The tool showed the following code: 61 -Pump motor or motor relay fault.

    Which part do I have to replace or is a there any method to erase/delete this code?

    Thanks in advance
    Mario
     
  2. Silvertwinkiehobo

    Silvertwinkiehobo The Lost Lamb

    Joined:
    Apr 21, 2014
    Messages:
    6,906
    Likes Received:
    1,168
    Trophy Points:
    505
    Location:
    Everett, WA
    Usually on ABS, a motor or relay problem is that when the computer commands the pump to pressurize the accumulator, either the relay doesn't latch (control or relay fault) or the pump motor fails to turn (no power or worn/seized motor/pump assembly). You need to first verify all the fuses for the ABS are good and allow power across it. I've seen these newer ATC and ATM fuses actually block power or the terminals open the circuit, so verify power at the fuses, power across the fuses. Then, if there's a same-part-number relay in the fuse and relay center, swap relays and turn on the ignition (don't start the engine). Listen for the pump motor to kick on. If it doesn't, then deeper diagnosis by a technician is necessary. Chrysler's ABS-10 system had an inherent problem that the accumulator would lose one of the seals and lose all pressure, so the computer would command the pump on and sit there pumping until the motor would overheat and fail. This is a possibility in other ABS systems, so have the tech verify the repair, and that there are no other hidden problems.
     
  3. Darth_Sidious69

    Darth_Sidious69 New Member

    Joined:
    May 5, 2017
    Messages:
    6
    Likes Received:
    2
    Trophy Points:
    1
    Thanks Andrew, I will try that the next days if it does not rain here. I will get back to you then.
     
  4. Silvertwinkiehobo

    Silvertwinkiehobo The Lost Lamb

    Joined:
    Apr 21, 2014
    Messages:
    6,906
    Likes Received:
    1,168
    Trophy Points:
    505
    Location:
    Everett, WA
    OK. Hey, if you can get a hold of a scan tool that not only shows data (such as accumulator pressure, pump motor status, etc.) but also has what are called "bi-directional controls," that would allow you to be able to read accumulator pressure, and then turn the motor on and off. That would help you immensely with determining if the relay or motor is at fault.
     
  5. Darth_Sidious69

    Darth_Sidious69 New Member

    Joined:
    May 5, 2017
    Messages:
    6
    Likes Received:
    2
    Trophy Points:
    1
    Hey Andrew. Sorry, but it took longer than expected.
    Unfortunately the scan tool does not have those "bi-directional controls". The power is ok across the fuses and
    there is no difference after swapping the relays. I have also tried to clear the code by jumping pin H to A on the
    Data Link Connector. I got this from a another forum. But it did not work.
    Maybe It will work when I replace the entire ABS modulator assembly as a unit. I´ll try first to get a used one here.
     
  6. Darth_Sidious69

    Darth_Sidious69 New Member

    Joined:
    May 5, 2017
    Messages:
    6
    Likes Received:
    2
    Trophy Points:
    1
    Correction. I will try to get an ABS Control Module first. The modulator is way to expensive at the moment.
     
  7. Silvertwinkiehobo

    Silvertwinkiehobo The Lost Lamb

    Joined:
    Apr 21, 2014
    Messages:
    6,906
    Likes Received:
    1,168
    Trophy Points:
    505
    Location:
    Everett, WA
    I'd suggest a 'pick n pull' trip, but unless the modulator is in other GM cars or trucks, there may not be any whales to get any parts from.
     
  8. Darth_Sidious69

    Darth_Sidious69 New Member

    Joined:
    May 5, 2017
    Messages:
    6
    Likes Received:
    2
    Trophy Points:
    1
    I have found a used Module from a 1991 Caprice Station. Perfect. Can you tell me where it is located?
     
  9. Silvertwinkiehobo

    Silvertwinkiehobo The Lost Lamb

    Joined:
    Apr 21, 2014
    Messages:
    6,906
    Likes Received:
    1,168
    Trophy Points:
    505
    Location:
    Everett, WA
    The reference site I'm consulting says it's in the left rear for '91, or above the instrument cluster on '92-'93.
     

Share This Page